StarCraft/Characters/Units

The units of Starcraft.

For the characters, check the character page. Head this way for the Starcraft II characters. For the units introduced in Starcraft II, go to the respective unit sheet.

SCV
""SCV ready!""

The workhorse of the Terrans, they're used to gather resources and construct buildings, as well as repairing damaged structures and mechanical units.


 * Fun With Acronyms: Space Construction Vehicle.
 * Magic Tool: Their drill can do anything, including cutting apart minerals, constructing buildings, and repairing units. In the sequel in allied games they can repair Protoss units too.
 * This Is a Drill: Although their weapon is listed as "Fusion cutter", it is quite clearly this trope.
 * Worker Unit

Marine
""Jacked up and good to go!""

The main force of the Terran squad, they're not very impressive in the HP or power department but make up for it with good versatility for their cost. A comparitively small squad of Marines with Stimpacks and Medic support is a serious threat if the opponent isn't prepared for it.


 * Cannon Fodder
 * Moves to Crouching Moron, Hidden Badass once you learn to use their benefits. A single group of marines start looking mighty scary with strong micro.
 * Cast From Hit Points: Stimpack, which costs 10 HP but doubles their movement and attack rates for a period of time.
 * Glass Cannon: Give them Stimpacks and get a decent sized group and they'll destroy anything in seconds. But they only have 40 HP so even with Medics they'll die if you so much as sneeze on them.
 * Luckily, My Shield Will Protect Me: Get a combat shield in the sequel that boosts their HP by 10 in Starcraft II.
 * Body Armor As Hit Points
 * Power Armor
 * Restraining Bolt: Because most Marines are conscripted criminals, they undergo neural resocializing to erase their memories and former personalities, giving them nice fake memories and rendering them completely obedient.
 * Space Marine: Provide the page picture

Firebat
""Need a light?""

A bulkier infantry unit armed with wrist-mounted flamethrowers, they excel at fighting lightly armored small units but are helpless against armored enemies and air units.


 * Arm Cannon
 * Cast From Hit Points: Shares the Marine's Stimpack
 * The Juggernaut: In Starcraft II they get the appropriately named Juggernaut Plating which upgrades their armor rating to 3, giving them the same defenses as a Battlecruiser.
 * Kill It With Fire
 * Power Armor
 * Pyromaniac
 * Video Game Flamethrowers Suck: As part of Crippling Overspecialization they can't attack air units and get a heavy damage penalty against armored units. As a result they're next to useless against anything that isn't a Marine, Zergling or Zealot, and even then they're outclassed by other units simply due to their melee attack.

Medic
""Please state the nature of your medical emergency!""

Introduced in Brood War, Medics can heal biological units, making the Terran infantry infinitely more useful by extending their longevity dramatically.


 * The Medic
 * Shoot the Medic First: In Starcraft II a new value assigned to units determines what targets the AI gives priority to killing. Medics get higher prioritiy than other infantry, meaning if it sees them the AI will try to kill them first.
 * Nanomachines: The official explanation for how their abilities work
 * Power Armor
 * Squishy Wizard: Averted, comparitively speaking--with 1 armor and 60 HP they're tied with the Firebat for having the best durability of the Terran infantry. Played straight in the sequel where they keep the same stats while everyone else got an HP boost.
 * Support Party Member

Ghost
""Somebody call for an exterminator?""

The Ghost's role in the Terran military depends on if you refer to the gameplay or the story. In the story they're the elite troops of the Terrans, covert assassins that demonstrate near-supernatural powers due to their incredible psychic abilities. In the game they're support troops that specializing in calling down nuclear bombardments and disabling enemies.


 * Awesome but Impractical: In the first game due to their position at the very top of the tech tree and the huge cost to train and upgrade them. Any decent opponent can also scout out your base, and the sight of a Covert Ops will immediately tip them off to build detector turrets around their base so they can see the Ghost coming.
 * Averted in the sequel where they're much lower on the tech tree, and out of the box without upgrades still make good supporters with Snipe and EMP Shot.
 * Cold Sniper
 * Crosshair Aware: Beware the blinking red dot if you see it in your base and find the source immediately!
 * Death From Above
 * Faceless Goons: To emphasize the fact that they have almost no humanity left, since they're subject to VERY heavy doses of brainwashing and implants.
 * Form-Fitting Wardrobe
 * Spy Catsuit
 * Gameplay and Story Segregation: As told above, according to the lore Ghosts are elite assassins capable of a variety of psychic abilities including mind-reading, astral projection, super-speed and reflexes, Hyper Awareness, and more. None of these abilities come into play in any game thus far, though Ghost would have included them in various capacities.
 * Invisibility Cloak
 * Psychic Powers
 * Restraining Bolt: Unlike the Marine theirs isn't just to keep them obedient, its to keep their powers in check.
 * Stealth Expert
 * Support Party Member
 * Telepathic Spacemen
 * You Nuke'Em

Vulture
""Alright, bring it on!""

Speedy hoverbike units, they're armed with grenade launchers and make excellent scouts due to their low cost and very high speed. They can also lay Spider Mines to surprise and ambush unsuspecting armies.


 * Badass Biker
 * Cool Bike
 * Fragile Speedster: They can outrun every other unit, especially once you upgrade their speed. Good thing, because most of those units will kill them in a straight-up fight.
 * Grenade Launcher
 * Splash Damage: Their Spider Mines.
 * Super Persistent Missile: Once a Spider Mine locks onto a target that comes in range, it'll leap up and chase it until it can explode on them.

Siege Tank
""Ready to roll out!""

One of the iconic units of the series, these are normal tanks complete with treads and turrets...until they switch into Siege Mode, where they become one of the most destructive forces in the game.


 * Glass Cannon: They can kill pretty much any non-air force, but being unable to move and unable to fire at targets too close means they're very easy to kill.
 * Hoist By His Own Petard: Their high power and Splash Damage can be turned back on an opponent through the use of melee units, thereby ensuring their units will take just as much damage as yours, if not more.
 * Large Ham: Arguably the hammiest in the game.
 * "Ride of the Valkyries": Sings it as a Stop Poking Me quote.
 * Siege Engine
 * Splash Damage: Combined with their massive range, its what makes them so deadly. They can't attack that quickly, but thanks to this trope they don't need to.
 * Tank Goodness
 * Transforming Mecha

Goliath
""Goliath on-line.""

Combat walkers, they're all-around solid units specializing as anti-air support.


 * Chicken Walker
 * Fun With Acronyms: Likes to list off several as Stop Poking Me quotes.
 * Gatling Good
 * Jack of All Stats: All-around decent HP, cost and damage output.

Wraith
""Wraith awaiting launch orders.""

The standard Terran starfighter, armed with missiles and lasers and protected by a personal cloaking field.


 * Cool Starship
 * Fragile Speedster: Very quick but low damage output and quickly blasted out of the sky when the opponent can fire on them. This is why their Cloaking Field is so vital to getting good usage out of them.
 * Frickin' Laser Beams
 * Invisibility Cloak
 * Space Fighter

Science Vessel
""Explorer reporting!""

A Terran support vessel equipped with technology to study the Zerg and Protoss and weaponry to deal with them.


 * Deflector Shields: Their Defensive Matrix.
 * Gameplay and Story Segregation: Science Vessels are basically space stations and are appropriately huge, and an entire mission takes place inside of one. In-game they're not much bigger than any other mechanical unit and smaller than most buildings.
 * Herd Hitting Attack: Irradiate
 * Nanomachines: Their Nano-Repair in the sequel.
 * Support Party Member
 * True Sight
 * Units Not to Scale: See above under Gameplay and Story Segregation

Dropship
""Can I take your order?""

Flying personal carriers used to ferry troops around.


 * Drop Ship: Duh.
 * Took a Level In Badass: Take one Dropship. Give it the Medic's Heal ability, thereby freeing up supply for more units since you don't need Medics and making your healer more durable and able to access injured troops more easily. Behold the Heal Bus Medivac.

Valkyrie
""Valkyrie prepared!""

A Terran starfighter introduced into the sector by the UED, they fire clusters of missiles are airborne enemies to decimate opposing fleets.


 * Gratuitous German: "Of course, mein Herr!"
 * Macross Missile Massacre
 * Put On a Bus: While some of the old units got replaced in the multiplayer, in-universe and in the single player campaign every unit from the first game is still being used in the sequel...except the Valkyrie.
 * Splash Damage

Battlecruiser
""Battlecruiser operational.""

The Terran capital ships, massive flying vessels with a lot of firepower and costing a lot of resources. If there's an important Terran character in the single-player, they're either commanding a Battlecruiser or serve under someone who does.


 * The Alcoholic: In the sequel. "The Yamato is loaded and so am I..."
 * Awesome but Impractical: A big case here in the second game. By the time you muster up the tech and resources required to buidl them, you would no longer need them nor would you want them. Their speed is atrocious, they cost too much, they have an energy bar (Protoss bait) and worst of all, are mostly useful against units with low armor. Comparing them to Ultralisks and Colossi is laughable at best. On the other hand as in II they are much more resilient, and can fire multiple rounds, and in fleet they are nigh unstoppable.
 * Beam Spam: In the original game, Battlecruisers attacked slowly but did high damage. The sequel takes them the exact opposite direction, giving them low base damage but attacking very quickly, resulting in this trope.
 * Deflector Shields: Get Defense Matrix in the sequel
 * Frickin' Laser Beams
 * Gratuitous Russian: Averted, but the pilot still has a definite Russian accent.
 * Lovable Coward: Has shades in the sequel.
 * Macross Missile Massacre: Missile Pods in Starcraft II.
 * Splash Damage: Missile Pods again.
 * Units Not to Scale: In the lore they're basically flying cities. In-game they're certainly one of the largest units, but still not to scale and are smaller than some buildings.
 * Wave Motion Gun: The iconic Yamato Cannon.

All units

 * Biological Mashup: The Zerg mostly resemble reptiles and/or insects, but many units combine aspects of both.
 * Big Creepy Crawlies
 * Insectoid Aliens
 * Reptiles Are Abhorrent
 * Divergent Character Evolution: In Starcraft II players can permanently upgrade a Zerg unit into one of two advanced forms in the single-player campaign, either form emphasizing different aspects of the base strain.
 * Fangs Are Evil
 * Fast Tunnelling: Their Burrow skill, though the Lurker and Ultralisk take a second or two longer to get underground than others.
 * Healing Factor: All Zerg units slowly regenerate HP.
 * Gradual Regeneration
 * Regenerating Health
 * The Unintelligible: All Zerg units except the Infested Terran only speak in growls, snarls and grunts.
 * Zerg Rush: They're the Trope Namers for a reason.

Drone
The Zerg worker, in charge of gathering resources. Can lay down on creep to mutate into the Zerg structures.


 * Worker Unit

Zergling
The basic Zerg unit, a dinosaur-like creature arms with fangs and claws to tear apart anything they can.


 * Divergent Character Evolution: The Zergling upgrades into either the Raptor or the Swarmling in Starcraft II. Raptors leap in on prey at short distances to quickly close in, Swarmlings produce three from an egg rather than two.
 * Glass Cannon: A pack of Zerglings with their upgrades will tear apart anything in seconds, as long as the target doesn't fight back--at 35 HP they're the second-weakest units in the game.
 * Power Gives You Wings: When they get their speed upgrade in the sequel they sprout locust-like wings.
 * Wings Do Nothing: For obvious reasons they don't actually let the Zergling fly.

Hydralisk
The Zerg ranged fighter, tensing its muscles to snap out needle spines from its shoulder plates as fast as any bullet.


 * Ballistic Bone
 * Sinister Scythe: Has preying mantis-like arms with blades extending from them.
 * Ornamental Weapon: Their claws, which, despite being thoroughly displayed in cutscenes, are rendered useless in the original game: They always use their ranged attack. In the sequel, Hydralisks use them in melee combat as a purely cosmetic attack with the same effective damage and upgrades as their ranged attack.

Lurker
An evolution of the Hydralisk, they're defenseless above ground. But once burrowed they can unleash waves of spines along the ground to impale enemies from below.


 * Giant Spider
 * Impaled With Extreme Prejudice
 * Splash Damage

Defiler
A specialized Zerg strain laying at the top of their tech tree, Defilers can support the swarm with the various toxins it can spew.


 * Poison Is Corrosive: Plague
 * Universal Poison
 * Hollywood Acid
 * Squishy Wizard: A well-placed Dark Swarm or Plague can punch a nice hole in the enemy's defenses, assuming the 80 HP Defiler can get the ability off safely.

Ultralisk
A massive Zerg breed that looks like an elephant if it was designed by Satan, they cleave enemies apart with their Kaiser Blades.


 * Elite Mook: They're basically the Zerg's ground-based answer to the Battlecruiser and Carrier.
 * Herd Hitting Attack: They deal Splash Damage when attacking in Starcraft II.
 * Lightning Bruiser: As befits the name, they hit hard and take a lot of damage, yet still move quite quickly. In Brood War, they are given a speed upgrade making them about as fast as zerglings, in Heart of the Swarm, they are given a burrow charge ability to quickly close with enemies.
 * Sharpened to A Single Atom
 * Sinister Scythe: The aforementioned Kaiser Blades.
 * Took a Level In Badass: As mentioned, in the sequel they now do Splash Damage, in addition to being immune to any ability that would incapacitate them and getting an HP buff. Fear them.
 * Also between the original game and Brood War, where they got upgrades for their armor and speed.
 * A variation on the Zealot's Charge ability shows in Heart of the Swarm. In it, the Ultralisk burrows while doing it.

Infested Terran
""Live for the Swarm!""

Have a Queen infect a Command Center and this is the result, a Zerg-controlled Terran that will sacrifice his life for the Overmind.


 * Action Bomb
 * Awesome but Impractical: As described under Glass Cannon below, they're too fragile to be of any real use, and that's assuming you can even infest a Command Center to use them in the first place.
 * Body Horror
 * For Massive Damage: They deal the most damage of any unit in either game, 500 to be exact, and Splash Damage to boot.
 * Glass Cannon: With 60 HP they aren't going to survive long. With 500 Splash Damage as an attack, the same can be said of their target if they can get there.
 * Taking You With Me
 * Took a Level In Badass: They're far more useful in Stacraft II and not just because they're spawned by a Mook Maker this time around. They're basically buffed up Marines with higher damage and HP. Their major flaws are their timed life and low speed, both of which are forgiveable if you use them properly.
 * You Will Be Assimilated

Overlord
A flying unit that provides the ability to control Zerg, any Zerg player should have far more of them than needed. They provide numerous other skills including detection and unit transport.


 * Giant Flyer
 * Power Floats
 * True Sight
 * Units Not to Scale: Eight Zerglings fit inside? Well comparing the Zergling model to the Overlord, passable. Four Hydralisks? Maybe if they cram in. Two Ultralisks? Yup, this trope must be in effect.

Mutalisk
The standard Zerg flier, they move fast and attack enemies by spewing Glave Wurms at them, which bounce off the intial target to harm nearby enemies as well.


 * Fragile Speedster: The next trope makes them deadly in the hands of a skilled player, but in a straight-up fight they're likely to get killed since like most Zerg they aren't very durable.
 * Hit and Run Tactics: They're infamous for this.
 * Leeroy Jenkins: in the first game at least, it is dangerous to leave them unsupervised, as the instant they see anything they can attack, they will hare off to do so. Even if it's, for instance, the entire enemy team.
 * Splash Damage

Scourge
Suicidal dive bombers, they sacrifice themselves to inflict heavy damage to enemy fleets.


 * Action Bomb
 * Glass Cannon: Only 25 HP but 110 damage.
 * Taking You With Me

Queen
The Zerg flying spellcaster, she supports the swarm with various delibitating abilities. The Queen of Starcraft II is listed with the Starcraft II units on that page since it is the Queen In Name Only.


 * Gameplay and Story Segregation: In the lore the Queen was always like the Stacraft II Queen, overseeing the base and helping the development of the swarm from behind the front lines. The original Queen was a support and harassment unit.
 * Spawn Broodling: Trope Namer.
 * You Will Be Assimilated: Their Infest Command Center ability, which does exactly what you'd think.

Guardian
A massive and slow-moving unit evolved from the Mutalisk, they fire globs of acid to destroy grounded targets from out of conventional ranges.


 * Giant Enemy Crab: While most Zerg are insectoid or reptilian, the Guardian carries a crustacian vibe with it.
 * Glass Cannon: Long range. High damage. 150 HP.
 * Hollywood Acid
 * Mighty Glacier: It's a good thing the Mutalisk is speedy because the Guardian is as slow as can be. It's far better to fly your Mutalisks to the attack point and mutate them there.
 * Siege Engine: An airborne variation.

Devourer
Another strain derived from the Mutalisk, they launch corrosive acid at enemy fleets that eat away at them and slow them down.


 * Mighty Glacier: Not as slow as the Guardian but still much slower than the Mutalisk. Also much beefier with 250 HP to the Guardian's 150.
 * Splash Damage: A curious variation, while in Brood War the Terrans and Protoss got the Valkyrie and Corsair to add this to their fleets, the Mutalisk already did Splash Damage, it just wasn't that strong. Solution - the Devourer itself doesn't do splash damage, but when it attacks the target and nearby units are splashed with acid spores that cause them to take additional damage and attack slower, thereby powering up the Mutalisk.
 * Support Party Member: See above.

All units

 * Deflector Shields: All Protoss units have personal shields that regenerate slowly and protect the unit from taking HP damage.
 * Glowing Eyes of Doom
 * One-Man Army: While the Zerg rely on swarms of little units, the Protoss have big beefy units with lots of HP and power, but high resource and supply costs.
 * Power Echoes
 * Power Glows
 * Shiny-Looking Spaceships

Probe
The Protoss gatherer, they collect resources and can place warp beacons to call in structures.


 * Frickin' Laser Beams
 * Ridiculously Fast Construction: Justified, the Probe never 'builds' anything, it places a beacon to mark a point to open a warp rift, and once the rift finishes opening the building is warped in fully constructed from somewhere else.
 * Worker Unit

Zealot
""My life for Aiur!""

The Protoss base unit, stalwart warriors armed with two psi blades extending from their wrists as an emination of the Zealot's psionic powers.


 * Blade Below the Shoulder
 * Dual-Wielding
 * Flash Step: In Starcraft II they get "Charge" which lets them quickly charge in on enemies when they get close.
 * Large Ham
 * Laser Blade
 * Lightning Bruiser: Fast normally, very fast with their speed upgrade, they do a good amount of damage, and they have enough HP to close in on enemies.
 * Powered Armor

Dragoon
""I have returned...""

A Protoss walker unit consisting of a robotic shell driven by the body of a wounded Protoss warrior contained within, they fire phase disruptors to attack.


 * Energy Ball
 * Fate Worse Than Death: How the Protoss see the unit, since they're piloted by badly wounded Protoss recovered from the front lines. They're Proud Warrior Race Guys, so to some of them being turned into a Dragoon is shameful compared to dying in battle with honor. According to the lore Dragoons are seen as outsiders in society for the same reasons.
 * Man in The Machine
 * Spider Mecha
 * We Can Rebuild Him

High Templar
""Khassar Detemplari...""

Protoss mystics that have foregone traiditional combat training to hone their psionic abilities. They can manifest illusions and call down storms of psychic energy.


 * Herd Hitting Attack: Psionic Storm
 * Heroic Sacrifice: How their Archon Morph is seen in the lore.
 * Hoist By His Own Petard: In Starcraft II they get Feedback, which lets them drain the energy of an enemy unit to inflict damage to them equal to the energy drained
 * Master of Illusion: Hallucination, which lets them create copies of a unit as distractions.
 * Mighty Glacier: Slow as can be, but with Psionic Storm they'll decimate anything they can see.
 * Red Eyes Take Warning
 * Shock and Awe: Their famous Psionic Storm.
 * Squishy Wizard: 40 HP and 40 shields, they are not going to last long.

Dark Templar
""Adun Toridas...""

Long ago, the Dark Templar rejected the Khala and so were branded traitors and outcasts, banished from Aiur. Reunited with their brethren in Brood War, they have learned to channel the energies of the Void to render themselves invisible.


 * Badass Cape
 * Blade Below the Shoulder
 * Dark Is Not Evil
 * Glass Cannon: Move at a respectable pace and do heavy damage, but very easy to kill due to their low HP and shields.
 * Instant Awesome, Just Add Ninja: How they tend to act in the lore, where they're treated as shady assassins. Also carries into the game, since they're best used in small teams as base raiders and scouts.
 * Invisibility Cloak
 * Laser Blade
 * Power of the Void
 * Red Eyes Take Warning
 * Sinister Scythe: In Starcraft II, though it has no effect on gameplay, Dark Templar randomly spawn armed with their original wrist-mounted Warp blades, or these.

Reaver
A Protoss robot equipped with on-board manufacturing facilities used to construct bombs called Scarabs. They move slowly but can decimate enemies.


 * Animal Mecha: Unambiguously a giant slug.
 * Mighty Glacier: A couple of good Scarab shots can cripple armies and destroy worker lines, but the Reaver moves incredibly slow.
 * Lightning Bruiser: But combine it with a Shuttle and it becomes this, able to slip into enemy lines, launch its scarabs, then re-enter the Shuttle and escape before defenders arrive.
 * Siege Engine
 * Splash Damage
 * Stuff Blowing Up

Archon
""The merging is complete...""

The pinnacle of Protoss psionic power, formed by two High Templar sacrificing their bodies to manifest as an orb of pure energy. They can decimate enemies with bolts of energy.


 * Cast From Lifespan: Within the lore Archons usually burn themselves out shortly after being created, which is why it is a...
 * Dangerous Forbidden Technique
 * Lightning Bruiser
 * Power Floats
 * Pure Energy
 * Shock and Awe
 * Splash Damage

Dark Archon
""We are as one...""

An ancient secret long forbidden to the Dark Templar for the sheer danger of it, the Dark Archon is formed by the dark energy of two Dark Templar merging together.


 * Awesome but Impractical: With Mind Control its possible to sieze an enemy worker, at which point you can build up that race's entire tech tree and construct their units. But given the time to do so and the difficulty in getting that worker...
 * Brainwashed: Mind Control.
 * Cast From Lifespan: Same as the original Archon.
 * Dangerous Forbidden Technique
 * Godzilla Threshold: In the lore, they were finally allowed to be born when rebelled and lead a Protoss force headed by Archons against the Dark Templar. None of the involved parties were particularly joyous that their war had come to this, which is why by Stacraft II the Dark Archon's creation is outlawed again.
 * Still it seems that with the renew conflict and the prophecy discovered by Zeratul, the Dark Templar either learned from the Khalai how to create normal Archons or the simply allowed the cretion of new Dark Archons but for gameplay reasons they apear as normal Archons.
 * Power Floats
 * Pure Energy
 * Red Eyes Take Warning: Red everything.

Scout
""Teleport successful""

The Protoss aircraft and the backbone of their fleet, they launch anti-matter missiles at aerial foes and photon blasters at ground targes.


 * Cool Starship
 * Space Fighter
 * Space Plane

Corsair
""It is a good day to die!""

Spacecraft designed by the Dark Templar, they move fast and launch neutral flares from their hull to rapidly attack enemies.


 * Cool Starship
 * Fragile Speedster: Fastest ship in the Protoss military, but easier to destroy than the Scout. When compared to the Wraith or Mutalisk however, that doesn't mean much.
 * Splash Damage

Shuttle
The Protoss transport, a simple carrier vessel that has the distinction of being the fastest transport of the races with its speed upgrade.


 * Drop Ship

Observer
A small flying drone armed with a cloaking field, it acts as a spy and escort, detecting invisible and burrowed units and watching points of interest.


 * Boring but Practical: They don't do anything except act as dectors, but their low cost, fast build time and decent movement rate makes it easy to deploy a couple. Their cloaking ability meanwhile makes them the ideal scout, able to slip into an opponent's base and see what they're doing without being caught, and they can be sent out in numbers to watch points of interest for opposing armies on the move or expansions under construction.
 * Invisibility Cloak
 * Spy Bot
 * Spy Satellites
 * True Sight

Carrier
""Carrier has arrived.""

The Protoss flagship, though they aren't armed with weapons of their own their hangar bays house swarms of small robotic drones called Interceptors that can be launched to fight for it.


 * Attack Drone
 * The Battlestar: The lore indicates that some of them have guns as well as drones. You don't ever have one of these kinds.

Arbiter
Support vessels piloted by members of the Judicator Caste, they act as anchors in reality for time-space rifts that render nearby allies invisible.


 * Awesome but Impractical: As with the Ghost higher up the page, they're very powerful fully upgraded but lie at the top of the tech tree and require a large investment of time and resources to deploy.
 * Energy Ball
 * Gameplay and Story Segregation: Their pilots, as members of the Judicator Caste, outrank you (the Executor).
 * According to Word of God, when Aiur fell the Judicator Caste was wiped out and the Arbiters abandoned. They're still around in multiple missions in Brood War.
 * Invisibility Cloak