The Dark Mark was described as the symbol worn by the followers of Voldemort. So did he actually have the mark himself? Obviously when he got a new body, it wasn't marked, so he used Peters- but I can't recall if he actually branded himself in the final 3 books..
Did Voldemort consider himself a Death Eater or was that the name he assigned to his closest followers?
Sure Voldemort founded the group and was its leader, but was it a title he assigned to himself?