Have any actors had an imperfection in their appearance that’s helped their career?

One I can think of right away. Robert Z’Dar.

That’s not plastic surgery, that’s his real face. He was born with a rare genetic disorder known as Cherubism which causes an unusually large jaw. Because the condition gave him an almost sinister appearance he was usually cast as villains or henchmen, often in low budget or direct to video films. He appeared in over 120 films and was instantly recognizable even if you didn’t know his name. In real life he was quite outgoing and disarmingly charming. He died of heart failure in 2015.