Almost every super-soldier ever (no, not you, Cap!) follows the 'looks okay, then goes berserk' model. A recent example would be Will Simpson and other recipients of Kozlov's Combat Enhancement drugs in Jessica Jones.
Come to think of it the MCU is chock full of that sort of thing: humans who were either predisposed to mental instability or went to the dark side after, say, being exposed to Terrigen or going through Stryker's lab and gaining non-obvious abilities. Or getting merged with a Symbiote at the Life Foundation (Eddie/Venom, or better yet, Drake/Riot). The Hulk probably also fits the bill.
Outside of the MCU, you've got brainwashing subjects like the Manchurian Candidate. I don't know that Dorian Gray counts as an experiment, but there was definitely external intervention to give a lovely veneer to a monster.
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Come to think of it the MCU is chock full of that sort of thing: humans who were either predisposed to mental instability or went to the dark side after, say, being exposed to Terrigen or going through Stryker's lab and gaining non-obvious abilities. Or getting merged with a Symbiote at the Life Foundation (Eddie/Venom, or better yet, Drake/Riot). The Hulk probably also fits the bill.
Outside of the MCU, you've got brainwashing subjects like the Manchurian Candidate. I don't know that Dorian Gray counts as an experiment, but there was definitely external intervention to give a lovely veneer to a monster.