8. Tim Curry - Dragon Age Origins
Tim Curry has been in many video games. His vocal performances (much like his roles on the stage and screen) range from subtle and effective to extremely hammy scenery chewing. He has performed a more complete range of villainous characters than any other living actor - From transvestite mad scientists to murderous clowns, scheming viziers, and Satan. He is a perfect voice to cast if you want to spice up your film/TV series/stage musical/game with a handful of delicious ham.
And yet, Dragon Age Origins is a unique role for him. Arl Rendon Howe (a prominent character in the human backstory for this multi-narrative epic) is not especially manic or even powerful. He's a secondary villain right out of the fantasy playbook: The power hungry nobleman.
But while the role is small, the presence of Tim Curry means that even if you are playing as a elf or dwarf (and thus miss out on a lot of this character's screen time), you have a built in knowledge that this slimy Arl is more dangerous than he's letting on.