Right! If he ain't gonna post a picture of himself then we can at least share our different visions of the mighty mysterious administrator of UD!
Julian Carter's Mental Vision of Luke
Right then! I've always imagined Luke as being of average height, say 5 feet 9 inches. (If he is, then I'm taller than him. I'm 6 feet 3 inches

). Thick black or brown hair and a beard. Brown eyes. Slim (not fat, but not skinny either). Deep voice; serious, but with a mischievous twinkle in his eye. 30 to 40 years old.
You might have noticed that certain physical features are inspired from the avatar Luke had when I joined UD. At that time, he had a pic of Chuck Norris with the flag of the US behind him.