Slade

""It's been a long time, hasn't it, Titans? A month, a year, a millennium? Far too long for my tastes anyway. I was beginning to think I'd never see you again!""

- ~Slade

For a time, Slade was one of the main villains of the series Teen Titans. He was seemingly obsessed with trying to bring Robin to the dark side, and even went as far as forcing Robin to be his apprentice. Slade appeared to enjoy bringing out the darkness of certain heroes which made Robin an easy target due to his flawed personality.