Potential spoilers for upcoming seasons of Game of Thrones. Don't read any further if you don't want to know anything.
Another popular theory among fans of A Song of Ice and Fire, and one that's relevant to the latest season, is the one that Sandor Clegane survived his wounds (infection in the book) and is serving at a monastery on the Quiet Isle. Brienne and Pod find themselves at the Isle and speak with the elder brother. He tells them of Sandor's demise while a man digs graves. Due to the events of the show, it would have to work a little differently since Brienne was involved in his defeat.
Evidence for the Gravedigger theory:
- The man that is digging the graves is described as very large, bigger than Brienne. His face is covered by a scarf, hiding any burn marks he might have. He has an injury that is very much like the one that "killed" Sandor via infection. The man also shows affection towards a dog that lives at the monastery.
- The Elder Brother, while claiming to have buried Sandor, is very vague about the subject. He never explicitly states that Sandor is dead, only that the Hound is. Fans think he means that the persona of the Hound is dead and Sandor lives on, freed from that identity. This is backed up by the fact that the Elder Brother himself claims that he "died" on the Trident as a warrior.
- If Sandor did truly die, it's doubtful there would have been enough time for the Elder Brother to learn as much about him as he has.
- Sandor's horse, Stranger, is stabled on the Quiet Isle. Stranger is notorious for refusing to let anyone but Sandor ride or lead him, so how else would he have been stabled?
- One quote from the Elder Brother can be used as an argument to disprove the theory:
"I buried him myself. I can tell you where his grave lies, if you wish. I covered him with stones to keep the carrion eaters from digging up his flesh, and set his helm atop the cairn to mark his final resting place."
While it appears this disproves any evidence to the contrary, fans of the theory insist the Brother is merely being metaphorical, or perhaps had to cut some of Sandor's flesh off to halt the infection.