Island Base

A Supervillain Lair (or a Hero's Headquarters) At Sea! Isolated from any inference of those pesky heroes, our resident baddies can concoct their schemes of world domination in peace. At least until the third act.

Bonus points if the island, or part of it, is shaped like a skull. Extra points for having an active volcano form part of the base, despite the obvious problems with heat keeping such things from being practical in real life.

Often equipped with a Den of Iniquity. See also Elaborate Underground Base, Underwater Base.

Examples of Island Base include:

Anime and Manga

Cyborg 009: An Island Base showed up in the first episode of the anime. It was used by two Mad Scientists like their Mad Scientist Laboratory.
Mazinger Z: Big Bad and Mad Scientist Dr. Hell had two Island Bases: Bardos, an ancient Greek island full of underground mazes and labyrinths where he found an army of Humongous Mecha: and Hell Island, an island near from the Japanese coast where he moved later in the series. It was a barren, rocky islet. A low mountain rose in the center, and several giant faces had been carved on its slopes. The Dragon Baron Ashura also had an Island Base doubled like a Cool Ship: the submarine fortress Salude.
- Great Mazinger: Marquis Janus' Home Base was at once a Cool Ship (it was mobile and could swim or dive underwater), an Island Base (it was shaped like an island) and a Volcano Lair (an artificial volcano had been built in the center).

Comic Books

Oolong Island served as a think tank for a number of Mad Scientists in the DC Universe. It is now where the Doom Patrol are based.
Monster Isle is the base of operations of the Mole Man in Fantastic Four
Titans Tower is on an island in Teen Titans
Blackhawk Island
The Triskileon in The Ultimates

Film

Most notable examples are with James Bond villains:
- Dr. No's Base was on Crab Key, albeit more of an Elaborate Underground Base
- Blofeld held headquarters on an oil rig in Diamonds Are Forever, technically an island.
- Kananga's island of San Monique in Live and Let Die, but it isn't really isolated: it has a tourist trade. Too bad - poppy fields, voodoo totems with guns, Baron Samedi and a Shark Pool.
- Fransisco Scaramanga's private island is probably the best example of the trope in The Man with the Golden Gun.
Nomanisan in The Incredibles.
Dr. Totenkopf's island base in Sky Captain and The World of Tomorrow (2004), complete with robots, prehistoric animals and a space ship.
Galaxy Island in Our Man Flint. Brainwashed women, a Weather Control Machine and an anti-American eagle.
Captain Nemo's island headquarters in the Disney version of 20,000 Leagues Under the Sea. Volcanic crater, submarine docking facilities and Self-Destruct Mechanism.
Yellowbeard. El Nebuloso's island, with a castle full of murderous monks.
The Nazi-controlled island in Raiders of the Lost Ark. More submarine docks, and an area where you can perform Jewish rituals. Watch out for exploding heads.
Baron von Frankenstein's island in Mad Monster Party.
Undercover Brother. The Man's island fortress.
Dr. Evil once held operations inside a volcano shaped like his head which was key geographical icon on a Caribbean island.
Spy Kids 2 had an island with a hidden base inside the volcano, and gengineered monsters running around.
Jurassic Park

Literature

Most of Billy & Howard and Duumvirate take place on one of these.
"Lincoln Island" is the headquarters of Captain Nemo and the harbor of the Nautilus in The Mysterious Island
The titular "Island of Dr. Moreau" by H.G. Wells.
Jurassic Park
In The 39 Clues universe: the Ekaterinas had a island base inside the Bermuda Triangle.
- The Madrigals have Easter Island as a base.
- There's also the Cahill ancestral home and the Gauntlet, on an island off the coast of Ireland.
In Soon I Will Be Invincible, Dr. Impossible used the same island base for 14 years before the heroes finally cracked it. At the climax of the novel, he returns to construct his new Doomsday Device in the ruins.

Live Action TV

Lost
The island of Mad Scientist Dr. Boris Balinkoff in the Gilligan's Island episode "The Friendly Physician".
Tracy Island from Thunderbirds.

Video Games

Fur Fighters has the last level set in a James Bond parody Island base...just off the coast of your hometown.
Mega Man Battle Network 3, the WWW has their base on an island, across the Demon Waters.
Metal Gear Solid's Shadow Moses Island is indeed an island - something the players (and at one point even Snake) needed to be reminded of.
In Phantom Brave, Marona lives on an island all to herself, called Phantom Isle, which she uses as a base. The Big Bad, Sulphur, also has an island of his own, called the Island of Evil, which he is sealed in.
Prison Island, though that's likely based off the concept of Alcatraz.
In Thief II: The Metal Age, the Cetus Project is run from Markham's Isle, a former pirate base taken over by the Mechanists. As you learn when you go there, the administration of the project is a bit complicated, but Markham's Isle certainly fits the Island Base and Elaborate Underground Base tropes.
In The Curse of Monkey Island, King André operates out of Skull Island. Subverted in that Skull Island really looks like a giant duck. It should be called Duck Island. And if you squint and turn your head it looks like a bunny. Well, it just says "Skull Island". It doesn't say a human skull.
Evil Genius goes for a twofer, having you tunnel into the mountain on your "Uninhabited Desert Island of Undisclosed Location (tm)". Midway through you're forced to move islands, because if you're going to use satellite-based doomsday weapons it's obligatory to launch them out the crater of an extinct volcano.
In Knuckles Chaotix, Dr. Eggman builds his latest Supervillain Lair on an island in order to get himself one step closer to several Chaos Emerald-like objects rumored to be hidden there.
Used and Lampshaded in Kingdom of Loathing; after your Nemesis pulls a Villain Exit Stage Left after your first battle with them, your class leader says they probably have a secret tropical island volcano lair. Sure enough, you eventually find a map to a secret tropical island volcano lair on one of your Nemesis's thugs and have a final showdown in the heart of the volcano, first with your Nemesis's normal form and then with its Demonic form. Troperrific!
The James Bond game Nightfire.
Dr. Nonookie's Nontoonyt Island lair in Leisure Suit Larry II.
Command and Conquer Red Alert 3 features a secret island base. A secret Easter Island base. In a volcano. With cannons in the Heads. That shoot bears.
The Cipher Headquarters in Pokemon XD: Gale of Darkness. They even have a machine that generates a constant storm around the island to prevent any unwanted visitors.

Web Comics

During the spy spoof arc of Dan and Mab's Furry Adventures, Dr. Jyrras' base is an island with an extinct volcano. Filled with orange pillows to simulate lava. It's supposed to be incredibly secret, but the agency has detailed plans.
Subverted in Sluggy Freelance:

Dr. Steve: It was your mistake to trespass on... [[[Dramatic Pause]]]... the Isle of Doctor Steve!

Torg: "Isle"? We're in the woods. I never left the mainland!

Dr. Steve: Do you know how expensive islands are these days?

Web Original

Villain Source (formerly Villain Supply) has options of either a Skull Island or a subterranean base on a volcano island.
Kate Modern Big Bad Michelle Clore's evil lair is located on (Real Life) Adak Island.
At the beginning of episodes of the Dr. Steel show, Doctor Steel's secret laboratory is shown to be on an island. Supposedly this island is located in the Pacific, near Hawaii.

Western Animation

Drakken and the Seniors both have island bases in Kim Possible.
Science Island is the headquarters for Jarvis Kord in Batman the Brave And The Bold.
Heroic Example: Tracy Island in Thunderbirds
The bunny-shaped island known as Bunny Island is the primary setting for Evil Con Carne.
Jonny Quest TOS. Dr. Benton Quest's island of Crab Key.
Phineas and Ferb Dr. Doofenshmirtz had a secret-hideout shaped island with the letter "D" carved into it.
- That wasn't Doofenshmirtz's actually, it was the lair of (one of) his mentor(s), Doctor Destructocon (Kevin to his friends).
Prometheus Black AKA, Meltdown has a underground lab on Dinobot Island in Transformers Animated. Blackarachnia moves into it later in the series. Apparently it used to belong to the government.
Cobra Island in G.I. Joe
The Legend of Korra has Air Temple Island where Tenzin and his family live.

Real Life

Principality of Sealand: A small former UK military installation used by various groups for a number of different purposes -- from radio to server room.
World War 2 involved a lot of these, which included:
- Pearl Harbor
- Fort Drum (AKA the concrete battleship)
- Corregidor
- the Channel Islands
- Betio
- Iwo Jima
Chagos Archipelago. It houses a massive US military base at Diego Garcia. It was used for reconnaissance in the 1973 Arab-Israeli war and saw wartime use in the first Gulf War. After 9/11 it was key to the wars in Afghanistan and Iraq. It may house nuclear weapons and may be a "black site" for detaining prisoners. It is more secretive than Guantanamo Bay - which is probably why most people have never heard of it.
- In a true supervillain fashion, forty years ago, its people, the Chagossians, were unceremoniously removed from their homeland by a joint operation of the United Kingdom and the United States, and essentially left beached in Mauritius as human detritus. This was detailed in David Vine's book Island of Shame: the Secret History of the US Military Base on Diego Garcia.