I remember reading some time ago that Benicio Del Toro made his character in The Usual Suspects mumbly because his only purpose was to die, so it didn't matter what he said.
It struck me this morning that Cedric Diggery very similarly served no purpose other than to die.
Other examples of this? My daughter and I puzzled over this a bit and concluded that if you're really narrow about it - they have to play basically no other significant part in the plot - we couldn't think of anyone else offhand.