Homestar Runner: The "Homestar Runner Wiki" is incredibly thorough about any information concerning the site. Want to know what each character is dressed as in every Halloween toon? Go there. Want to know what computers Strong Bad used? They got it all sorted out. Want to know obscure stuff like Bubs' shady deals? They got it. The Brothers Chaps have admitted they sometimes use it for reference about their own work, have donated to it for years, adopted a character's fan nickname from the wiki (the Visor Robot) into canon, and even acknowledge its existence in several toons (such as "Fan Costumes 2016"). Taken up to eleven with the StrongBadActual Twitter account, which is probably the only one whose relevant Wiki documents all its posts in detail.
Crossover on other wikis:
CN City: The era itself has an article on both the CN Wiki and the OK KO Wiki, and several of The City's potential constituent locales (going by both the bumpers themselves and "Crossover Nexus") have deeper coverage on their shows' dedicated Wikis.
Stylistic Suck articles used to have their own dedicated side wiki, Craptendo.
Fantendo has also inspired the creation of many other wikis. The more blatant clones over the years include Faketendo, Fanontendo, Fanintendo, Fanintendo 2, Fanfantendo, Sweartendo, Newfantendo, NEXT Fantendo, Super Fantendo, Random-ness Fantendo, two Ultimate Fantendos, two Fantendo 2s, two Fantendo IIs, a Fantendo Two, a Fantendo III, a Fantendo lllnote that's three lowercase Ls… The Untenexpy Blue Soup was transplanted from one of these wikis into the Fantendoverse, where he serves as a Doppelgänger.
Pony Chan: Gyropedia: The Ponychan Wiki. Tends to attract more vandals than contributors. However, a couple of attempts have been made to reclaim the wiki. None thus far have made much progress.
TWICE: the Twice Wiki contains not only information about the members, but also a small handful of song meanings, color-coded lyrics, and English translations of most songs.
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