Space Cold War

The Cold War! Recycled in SPACE! Considering it lasted about 45 years, the Cold War massively influenced speculative fiction and fantasy work during and after that period.

Metaphors and analogy about nuclear weapons, superpower rivalry, communism etc. therefore were common.

Note that this is not entirely without rational foundation, a technology capable of interplanetary (or even moreso) interstellar travel necessarily involves energy levels and destructive possibilities on a grand scale. Mutually Assured Destruction is quite plausible in a war between space-faring powers, making scenarios at least akin to the Cold War not entirely unlikely.

Please note this entry is limited to exterior settings inspired by the Cold War and not stories that explicitly involve the actual Cold War.

Fan Works

 * In the Fusion Fic Renegade, this is the state of affairs between the Citadel and the Global Defense Initiative. It's less antagonistic than most cold wars, but GDI and the Citadel are at serious odds due to GDI's outright refusal to adhere to Citadel laws regarding dreadnought production or AI tech. Not to mention GDI's attack on the Batarian Hegemony....

Literature

 * The first two Honor Harrington novels have a cold war going on between the Star Kingdom of Manticore, and the People's Republic of Haven, that has been ongoing for half a century before the first story starts.
 * Embedded has a Cold War ongoing between the NATO-style United Status and the Warsaw Pact-style Central Bloc. It's mostly identical to the original Cold War, except that the two powers are more opposed politically instead of ideologically. Also, thanks to the vast room available on the hundreds of colony worlds, the two factions aren't brought into conflict very much.
 * A significant portion of the Legend of Galactic Heroes falls into this, as by beginning of the series the centuries long war between The Empire and the Alliance generally devolved into the Cold-War-with-occasional-skirmish mode and it took the rise of Reinhard and Wen-Li—the titular Heroes—to the top of their respective societies, for conflict to intensify again.
 * Urras in The Dispossessed is in the midst of a cold war intentionally reminiscent of the real one, with the players being the liberal, parliamentary republic A-Io and the socialist totalitarian regime Thu. When a war breaks out, they don't attack each other but rather help different sides of a conflict in the underdeveloped country of Benbilli, which bears a suspicious resemblance to Vietnam.
 * C. J. Cherryh's Alliance Union has one with three factions: Sol (Earth)/Alliance/Union. All are capitalist, though it is noted that Union citizens mostly descend from eastern block.
 * In the Star Trek Novel Verse, the Typhon Pact vs the nations of the Khitomer Accords. Six previously antagonistic races, the Breen, Gorn, Tholians, Tzenkethi, Romulans and Kinshaya, formed new galactic superpower the Typhon Pact, which is a rival to the United Federation of Planets. The Federation responded by expanding their alliance with the Klingons to also include the Ferengi and the Cardassians, while also courting the Talarians. Now there are two large political blocs competing politically, economically, and technologically.

Live Action TV

 * The relations between the System Lords in the earlier seasons of Stargate SG-1.
 * Other episodes in the Stargate Verse (such as "The Game" in Stargate Atlantis) have done this too.
 * The basic concept has featured in Star Trek between the Federation and multiple alien races at different times; the Klingons in Star Trek: The Original Series were outright metaphors for Soviet expansionism, while other series had the Cardassians, the Dominion (until actual war broke out) and finally the Romulans in spades.
 * Enterprise featured a Time Travel cold war called the Temporal Cold War. Interestingly, the incipient Federation played the part of third world in this conflict, being used as a pawn between two secretive factions who were neither of them the nice guys, even if one was the "good" guys.
 * Of course, a future version of the Federation was at least one of the sides of this rather confusing, and clearly not thought entirely through, cold war.
 * To elaborate more on the Star Trek analogies, The Federation was the idealistic, peaceful Western (read: American) society. The Klingons took up the loud, arrogant, warrior stereotype of the Russians, while the Romulans assumed the sinister, backstabbing, espionage/sabotage-laden stereotype of the Soviet Union, especially the Tal Shiar, which was the KGB in disguise. In an extremely apropos metaphor, the Klingons and Romulans switched from being allied to at war to being allies again at the drop of a hat.
 * That or the Romulans were an analogy for the Chinese, the secretive and testy on-and-off allies of Soviet Russia.
 * The Doctor Who stories "The Armageddon Factor", "Timelash".
 * Also "Frontier in Space," in which a third party is provoking a (second) war between the humans and their enemies, the Draconians.
 * Farscape is set against the backdrop of rapidly rising tensions between the Peacekeepers and the Scarran Empire. The war finally turns hot in the miniseries.

Tabletop Games

 * In Traveller the Imperium is in a cold war-like state with the Zhodani on the Spinward Frontier, and the Solimani Confederation on the Rimward.

Video Games

 * Star Wars: The Old Republic: The setting for the game, is a cold war that was established, when, after invading The Republic for decades, the Sith Empire sacks their capitol, and forces them to sign a peace treaty. The Empire's motivation for signing the treaty, which gives the empire a bunch of strategically insignificant worlds, is a great mystery, and the Emperor disappeared soon after it was signed. This cold war brings the idea of an arms race to it's logical conclusion: planet destroying weapons, besides the usual proxy conflicts and special forces operations. Both sides are positively chopping at the bit for the war to go hot again, and the facade of peace breaks down over the three acts of each of the game's eight class story-lines.
 * X3: Terran Conflict has a cold war between the Terrans (Sol system human government) and the Argon Federation. The Terrans are paranoid that the Argon are dabbling in artificial general intelligence research, and the Argon fear the Terrans' extremely advanced technology. Terran Conflict's main plot follows some of the events that set off the war that takes place in the expansion pack, Albion Prelude, when the Argon blow up the jewel of the Solar System, Earth's Torus Aeternal and sic artificially intelligent fighters on Earth's fleet. This war ends up being a Shaggy Dog Story: as the Argon push the Terrans back to the inner planets, the Ancients shut the whole jumpgate network down and trap everyone in the entire X-Universe where they are.
 * The entire premise of Battlezone 1998, with the U.S.A. and USSR duking it out on various planets and moons of the solar system with advanced Hovertanks realized with a biometal of alien origin.
 * This is a possible interpretation of the relationship between GDI and Nod between games. It's not a straight example since both sides are still Earthbound, but it fits if you interpret the trope broadly as "fictional cold war".
 * Despite being a declared war, the fighting between the Federation and the Auroran Empire in EV Nova has devolved to this, with frequent border skirmishes. Reason being, the last time the war went full-scale, both sides struck far behind the lines and millions of innocents died, forcing the combatants to devote the bulk of their forces to Home Guard duty.