2. Lord Voldermort (Harry Potter)
Lord Voldemort (formerly Hogwarts student Tom Riddle) is considered to be the most powerful dark wizard of all time in the world of Harry Potter. Not happy with the fact he had a muggle (non-powered human) Father, he changed his name to Voldemort to distance himself from that background (he wanted to be a 'pure-bred') and set about spreading evil wherever he went. He amassed a huge following of of witches and wizards who called themselves, collectively, 'Death Eaters'. Many of his followers joined Voldemort through sheer fear of him, giving you an idea of why he is a suitable candidate for induction in to the Sinestro Corps. In fact, very few people in the Harry Potter universe are brave enough to even speak Voldemort's name - his reputation as a fearsome individual is so widespread. Voldemort's impressive magical abilities combined with the powers of a yellow ring would make him an incredibly dark and dangerous foe and a terrifying Sinestro Corps member.