Another HERO PC with silly elements, but no silly drawbacks per se was Rōg Tus-karr.
Conceived as a version of pulp-era/Sci-Fi types like Adam Strange, Flash Gordon, Buck Rodgers and Commando Cody, he's a crash landed alien scout, a heavyworlder. He has some advanced sensory & survival tech in his uniform, plus some jump jets and a handy blaster pistol for a sidearm. Has a small, golden bird-like robot drone for recon, too. As a heavyworlder, he is physically stronger and more durable than humans. He looks like a bipedal, 7'8" tall pink elephant. Home world: Snuffleupagron 5. Because of looking like a giant pink elephant, winos hate him (potentially a minor but silly drawback).
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I was in a group that helped playtest GURPS Vampire the Masquerade. While there were no real drawbacks I can remember, the entire character concept I used was inherently a drawback- he was based on Blade…and NEC’s The Tick.
He was a private detective who had been turned by a powerful Brujah, and when he returned to unlife, the only way he could rationalize his new superhuman strength, toughness and speed was that he had become some kind of superhero, Major Mosquito. IOW, he went nuts. He also vaguely remembered something about vampires, and decided to kill the bad ones he encountered (along with some of the mortal villains). Because he was a Vampire Hunter, he kitted himself out with things like body armor, crossbows and such. And surgical steel “crime straws” to suck the blood of criminals.
So what you had was an insane, vampire-hunting vampire who was an extremely powerful melee combatant. His true clan felt he was too crazy to be of their kind, and foisted him off on the Malkavians. The Malkavian in the party manipulated him into NOT killing the other vampires in the group…while giving him PLENTY of other targets to take out.
IOW, every vampire encounter outside his core group of bloodsuckers was always on the verge of turning into a bloodbath. And not the kind that vampires enjoy.