the trouble with Barty Crouch Jr (even leaving aside the David Tennant connection) is that he's neither old nor ugly nor fat nor any of the things that the main list was created for. It's true he's not used often (certainly not often enough *g*), but he's not really unappealing (except for, you know...being a death eater)
Mind you, once the sign ups started, the list was frozen for this year, but there's nothing to keep you from pairing Barty with one of the "allowed" characters on your recipients list. :)