"Bad End Friends" refers to a niche sub-genre of grimdark fan art depicting young protagonists from various animated properties in tragic, corrupted states, more often than not entailing some form of possession by malevolent entities and usually derived from canonical situations in which such fates were threatened or temporarily induced, although some cases take more creative liberties to the end of imagining a specific “bad end” for a given character. Some of the most commonly depicted subjects include Dipper Pines from Gravity Falls (possessed by Bill Cipher), Finn from Adventure Time (corrupted by the ice crown) and Coraline from Coraline (eyes replaced with buttons). Most of the artworks depict two or more characters together in a crossover context.

The "Bad End Friends" content and surrounding fan interest are most prominently visible on Tumblr and DeviantArt, and the sub-genre appears to be closely related with the so-called "Mystery Kids" fandom, which regularly depicts the standard versions of many of the same characters in similar crossover contexts and is formally documented on TVTropes. The Wikia domain dedicated to the premise hosts character concepts on a user-submitted, site manager-approved basis.

Despite its visibility as a clear subject of specific interest, the exact origins of the trend are poorly documented; a YouTube video attempting to explain the fandom exists on the channel of user Sans Review, but is entirely in Spanish, and the English meaning of its contents has not been verified at the time of this page's submission.

As evidenced here, the genre appears to have been established and peaked around 2016.