Although you might not immediately associate the two, Roy Keane and Darth Vader are very, very similar.
One grew up in a barren wasteland and eventually rose to become a ruthless tyrant whose name struck fear into the hearts of men. The other was created by George Lucas and voiced by James Earl Jones.
Not only that, Keano and Darth Vader are both highly respected warriors, although one likes to choke people out using his mind whilst the other prefers to death-stare (heh) people until they repent and beg forgiveness. Either way, it's the same outcome.