History UnexpectedCharacter / WesternAnimation

* ''WesternAnimation/ThePenguinsOfMadagascar'': Everyone assumed [[spoiler: Manfredi & Johnson were ''[[PosthumousCharacter dead]]'']], so imagine the fandom's collective surprise when they appeared [[spoiler: alive]] in "The Penguin Who Loved Me."

** "[=SpongeBob SquarePants=] vs. the Big One" has the Flying Dutchman [[ItMakesSenseInContext end up in Davy Jones' Locker,]] where he comes face to face with Davy Jones [[spoiler:of Franchise/TheMonkees]] himself.

* Amongst the characters seen on ''WesternAnimation/JusticeLeagueAction'' are Space Cabbie (an obscure Silver Age character who's ExactlyWhatItSaysOnTheTin), ComicBook/JohnConstantine (a traditionally very much unkid-friendly character prone to swearing, chain smoking, and screwing people over), ComicBook/SwampThing (whose stories ever since Creator/AlanMoore's run are also very unkid-friendly and who Constantine spun off from), ''[[ComicBook/BatmanAndTheOutsiders Outsiders]]'' foes the Nuclear Family, Carmine Falcone (though time travel was involved in that one, but still he's a foe from Batman's [[ComicBook/BatmanYearOne in-universe]] [[ComicBook/TheLongHalloween early years]] and a normal mafia don, which is normally outside of the League's greater purview), ''ComicBook/HouseOfMystery'' host Cain, Dex-Starr ([[AmazingTechnicolorWildlife a blue-furred house cat from Earth]] who's a member of the Red Lantern Corps), Superman Red/Superman Blue (an old Silver Age {{Elseworlds}} story, a subsequent part of the [[AudienceAlienatingEra infamous]] Electric Superman phase, and [[spoiler:''ComicBook/SupermanReborn'']], where Superman split off into two beings, one red and the other blue), [[spoiler:Despotellis (a sentient virus that's a member of the Sinestro Corps), and Aya from ''WEsternAnimation/GreenLanternTheAnimatedSeries''.]]

* When ''WesternAnimation/TotalDramaRama'' was announced as a SpinOff for the ''WesternAnimation/TotalDrama'' series, several fan-favourites were confirmed to appear, such as Owen, Duncan, Courtney... and Jude from ''WesternAnimation/{{Sixteen}}''. Granted, the shows were made by the same company and share several voice actors.

* ''WesternAnimation/{{Batwheels}}'' is an upcoming cartoon aimed at preschoolers where the Batmobile and other related Batvehicles are sentient beings working alongside Batman to fight crime in Gotham (Think something like ''Franchise/{{Cars}}'' or ''VideoGame/PuttPutt'', but with ''Batman'' characters). And of course, both Robin and Batgirl are also in the supporting cast. What's surprising in this case however is who the Robin and Batgirl of this series are instead of the usual Dick Grayson and Barbara Gordon. Robin in this series is Duke Thomas, who didn't even hold the Robin identity for that long in the comics and eventually went on to become the Signal. Batgirl meanwhile is [[ComicBook/Batgirl2000 Cassandra Cain]], who's...not a kid-friendly character with kid-friendly lore, even by ''Batman'' standards.

** The addition of Franchise/SpiderMan might have caught some viewers by surprise, since he rarely makes guest appearances in other Marvel characters' cartoons. (The previous time he had a speaking role in someone else's show happened over 30 years earlier, in ComicBook/SpiderWoman's animated series.) Additionally, none of the previews or trailers for the second season showed him, at least not before the season began. It seemed even more unexpected for [[spoiler:Spidey to become a reserve Avenger]].

** The show [[AdaptationDrift stopped adapting]] ''Literature/TheRailwaySeries'' after season 4 in 1994... until the hithero-AdaptedOut Mike, Bert, and Rex appeared in ''WesternAnimation/SodorsLegendOfTheLostTreasure''.