Shalky appeared in the Paul Cornell webcast Scream of the Shalka and was promptly forgotten when Ecclescake came along. Also stars in Withnail and I. He was gay for the Mattress and no, that's not a joke, that's 100% canon. Even more canon than the story. Also I bet you some fans will just say that the Shalka doctor was really the real 13th doctor all along aka new audio visuals.