The Turret Master

In the realm of Video Games, most know of The Beast Master and The Minion Master. Their major strength comes from their summoned companions. The Turret Master takes similar cues, but places his defense more in line with technology and traps.

In a nutshell, the Turret Master is a character with the ability to summon a stationary defense in the form of an automated Turret. Bear in mind this needn't be a literal turret: it can be anything that fulfills the general role of a stationary defense, even if it's just Torchlight's stick that shoots fire.

What exactly this ability entails varies a bit: Some suffer from Weak Turret Guns, while others are invulnerable but on a restricting timer. Oddly enough, it's more common for a character like this to be fairly powerful even without this ability than to be a Squishy Wizard as The Minion Master commonly is. This ability is more common in Rogue- or Archer-styled classes. Classes like this can also usually form other traps, as well.

You play one of these in most Tower Defence games.

Examples of The Turret Master include:

The Assassin from Diablo 2 is one of the earlier forms of this, having a line of Trap abilities that worked to summon turrets. A similar idea existed in a spell, called Guardian in the first game, and Hydra in the next two, which would summon a three-headed beast that would shoot firebolts.
Similarily, the Arbiter skills for Torchlight's vanquisher class is based on this.
The Assassin from Warrior Epic, an obscure Diablo-inspired MMO.
Jack and Angie Shirly from Granado Espada: Jack can use a spear, but Angie has this as her only line of defense.
The Engineer of Team Fortress 2 - known enough to be page's image. The basic sentry takes a while to be erected, but can be upgraded to be a rocket-shooting, dual-minigun-equipped monstrosity (pictured), capable of denying access to the covered area for almost any enemy. He also has a different kind of a turret - a mini-sentry, weaker but cheaper and capable of being quickly deployed in just about any place to persistently bug enemies, as it's likely that another will be quickly re-established somewhere else. Only one can be built at any time, though.
Another FPS example is Roland of Borderlands. His skills are an amalgamation of this and The Medic.
- Borderlands also has the Crimson Engineer and Combat Medic enemies (which drop turrets and healing tower...things, respectively), as well as the badass versions of the shock/pyro/chemical troopers (which drop elementally specific turrets). The reason Roland has the same abilities is because he was a former Crimson Engineer.
Mass Effect 3 has several examples.
- The Geth Engineer in multiplayer can deploy a turret that shoots at enemies and restores friendly shields.
- The Human Engineer has a similar ability in the Combat Drone, but the Drone is mobile where the turret is stationary.
- The Cerberus Combat Engineer can also deploy a turret.
Weavel from Metroid Prime Hunters can turn the lower half of his body into a sentry turret.
Devices Blasters in City of Heroes have access to a power that summons a turret. In practice, it's not all that great.
- Had. Now the power summons a flying gun drone. It's not any better. Meanwhile, Traps users can lay down a little mortar lobbing acid shells. While a poor damage dealer, it's a very good debuffing tool.
Krotera from Iji: You could actually damage him by kicking the turrets at him.
Brink has an engineer class who can do this.
Dwarven Engineers in Warhammer Fantasy Battle Online can build several different types of Steampunk turret, up to and including flamethrower and grenade launcher turrets.
Heimerdinger from League of Legends builds turrets as his main method of offense. If you level them up enough, their bullets will begin exploding, and another ability causes them to freeze the enemies.
Bioshock 2 has a new breed of Big Daddies called "Rumblers", which have shoulder-mounted RPGs for crowd control, as well as portable miniature-turrets for scattered enemies. While the player character can also deploy any mini-turrets he comes across, he can only hold as many as four on him. The Rumbler, however, can throw as many as he'd like while within combat.
- The Security Command plasmid can turn the player into a temporary Turret Master, directing both stationary and mini-turrets towards whatever he wished. Thrown at a Rumbler, it will make his own turrets fire on himself as soon as they land
A rare Roguelike example: In Caves of Qud, you can make turrets out of any gun. Yes, you can even make a musket turret.
The turrets dropped by the Ranger class tree in Dragonica are by far their most damaging attacks and can make bosses evaporate. However, they're laughably easy to avoid in PVP (one has a slow firing rate and slow projectiles while the other only shoots straight ahead), robbing the class tree of much needed attack power.
Monday Night Combat is sort of weird about this; any class can set up a turret in one of the designated areas as long as they can pay for it. However, the Support uses his Firebase ability to deploy a smaller turret anywhere he likes that can buff teammates at the highest level. Super Monday Night Combat adds the Combatgirl, who can plant up to four small "Combat Kitties" at a time and fortify nearby turrets, increasing their defense and rate of fire for a brief period. The Gunner class can also use his Deploy skill to lock himself in place and effectively become a turret.
The Robotics class in Global Agenda has a variety of turrets among his repertoire, but can also be The Minion Master via the use of the robotic drones that give the class its name. It's a matter of the player's preference as to which one they prefer, if it isn't both.
The titular character from Lock's Quest often uses turrets as his main form of offense, it being an action/tower defense hybrid. He also has traps, walls, and minions at his disposal, making him a Trap Master and a Minion Master... but not a Wallmaster. That's something else entirely.
Guild Wars 2 will have the Engineer profession, known to be adepts at placing turrets around the battlefield, compared to the spirits of the original Guild Wars.
Champions Online has, as one of the available powers in the Gadgeteer set, a combat drone. By clicking one of the buttons on the pet command bar, you can transform it into a surprisingly effective stationary turret.
The Tactical class in Earth Defense Force: Insect Armageddon can choose three deployables to use prior to starting a mission. There are five turrets types; Machinegun, Plasma Grenade, Missile, Autocannon and Rocket, along with a Sensor Post to track enemies, and also two types of Land Mine.
The title character in Soulcaster is a wizard who summons ally warriors to fight for him. But unlike a typical Minion Master, they're stationary, and the end result plays like a fantasy version of this trope.
In Hellsinker, if Kagura is equipped with Epileptic Chariot, she can be played like this.