star trek episodes about a "sentient AI" turning out to be stolen human brains put into computers by a mad scientist, by series
tos: the episode is based on the fact that the stolen brain is a Woman and she needs love too
tng: the mad scientist is a sort of an annoyingly dressed flashy guy who's annoying and we're all glad to see him exposed for this by data who makes a quip about being real sentient AI. picard has a moving speech abt how stealing brains is bad. deanna should have sensed the brain but she doesn't bc she's not in the episode
voy: they find the brain when it starts decomposing and realize that it has been powering the ship the entire time. they encounter trouble when they realize it won't work without a human brain. an engineer gets into an accident and falls onto an incurable coma and they decide it's what they would have wanted and put their brain in but the funeral is really sordid and nobody can look at each other the same after
ds9: julian bashir tries to solve the brain's problem by growing a headless body in a vial to give it to the brain to use. but the headless body escapes and trouble arises when quark refuses to give it back bc it became his best dabo consumer. this is plot B. plot A is the terrifying reality of war
ent: alien kidnaps archer to use as the brain donor but lets him go as the brain scan turns out to be negative
disco: it's in season one or two. all klingon ships run on stolen human brains and this isn't really remarked upon by anybody at all but the floating brains are good set dressing to a scene when ash tyler is breathing heavily and making tortured faces abt having a klingon in his bones