Couldn't find very many pictures of him that weren't statues, but in everything I did find, modern or ancient, gave him a black beard. That second picture makes it look like it might be a little gray though (stress from running the underworld for eternity?). read more
As Hades is a mythological person, it's impossible to say for sure. However, from statues it can be seen that he had a full head of hair and a beard. read more