A term for wild, off-the-wall theories. Named after a leading tinfoil-hat theory explaining the mysterious shaking, rustling trees on Lost during its first season. The theory? The trees were having epileptic fits.
Although Lost has long since run its course, the image remains a potent title for the trope. No matter how absurd or irrational a theory (or tree) might seem, if it has enough ground, in the eyes of enough fans, it can spread new branches, seed new ideas, and eventually come to influence the entire work.
Crazy theories are not only common, but expected; especially for mystery series already host to its fair share of Mind Screw. An ongoing series which uses Chekhov's Gun to the point of becoming a Chekhov's Armoury encourages Trees because all newly introduced objects, people, skills, etc. will eventually be suspected of being a Chekhov's Gun. See Stock Epileptic Trees for common species of Tree such as Everyone Is Jesus in Purgatory or All Just a Dream. Not to be confused with Aluminum Christmas Trees. Has nothing to do with Epileptic Flashing Lights.
Epileptic trees that portend something so terrible or disappointing that everyone hopes they aren't true are known as Poison Oak Epileptic Trees. Epileptic Trees suggested in-universe by the characters themselves are a sign of Scully Syndrome. When an Epileptic Tree is rendered null and void by the official canon, it's said to be Jossed. When an Epileptic Tree becomes canon, you're allowed to say "I Knew It!" — unless Word of God reveals it became canon because it was an Epileptic Tree, in which case it's Ascended Fanon. See also Inferred Survival, Urban Legend of Zelda and Schrödinger's Butterfly. Compare conspiracy theories, Epileptic Trees about Real Life.
If you'd like to see the wiki contributors' own personal epileptic forest, check out our Wild Mass Guessing page. Don't waste your tree here — go plant it in Wild Mass Guessing.