"I am responsible for bringing somebody back that you think you're never going to see again. I'll leave it at that," he told Pop Goes the News.
McShane will only appear in one episode of Season 6, but it's been previously reported that his character holds "key importance." There's long been speculation that McShane is taking on the role described in a casting call as a gruff ex-soldier who has become a rural priest ministering to the poor. This could easily be the show's version of A Feast for Crows' Septon Meribald, most likely with little Elder Brother mixed in. If this is true, it stands to reason that the character McShane discusses bringing back is none other than the Hound (Rory McCann), whom Arya left for dead in Season 4.
In the books, Brienne meets the Elder Brother on the Quiet Isle who claims that the Hound is dead and that he buried the body himself. However, the gravedigger in that scene is large man whose face is covered by a scarf and bears similar injuries to the Hound.
While McShane's words may be nothing more than wind, it is looking more and more likely that both the Hound and Jon Snow will be back from the dead next year.