Dorian Gray is a man who became immortal due to a magic portrait of himself. Every year his image in the portrait ages a year while Dorian himself remains young, and whenever he is injured the painting takes the damage while Dorian instantly regenerates. However, if his portrait is ever destroyed, or if he looks at it directly, all of the wounds the image displays will be visited upon Gray in full, effectively killing him in a very gruesome manner.
Dorian does not have a role in any of the comics. His portrait hangs in the Secret Annex, suggesting he was a member of a mid-19th century League.
Dorian does have a large role in The movie, in which he is played by Stuart Townsend. In the movie he is an active member of the League, but eventually reveals himself to be a spy working for James Moriarty. He is killed by Mina Murray when she forces him to look at his painting.
Dorian Gray is from the novel The Picture of Dorian Gray by Oscar Wilde.