The upcoming sixth season of HBO's "Game of Thrones" will see the return of a handful of old cast members such as Isaac Hempstead-Wright (Bran Stark), Gemma Whelan (Yara Greyjoy) and others who haven't been seen in some time. Now, we can add one more name to that list.

VivienneClore, the talent agency that represents actor Paul Kaye, confirmed that its client will be returning to Westeros to appear in Season 6. If you're scratching your head and wondering, "Who?," we don't blame you. Kaye was last seen way back in Season 3 as Thoros of Myr, a follower of the Lord of Light (Melisandre's religion), who was able to resurrect Berric Dondarrion several times.

After mentioning his theatrical work, the agency wrote in a news release: "Paul has also been busy with television roles, you can catch him in the eagerly awaited Season 6 of 'Game of Thrones.'"

Thoros is a key member of the Brotherhood without Banners, though the group's role has been downplayed in the show. It's been rumored that Kaye has been filming some sort of hanging scene, which could hint to his character following a very similar arc as he does in the books. Does this mean we're in for a Lady Stoneheart sighting? Probably not, though it is possible that a different character (Sansa?) assumes that leadership position with the story line from the books progressing in the same way on screen.

Based on the Season 6 casting call, we know that there are several new outlaw characters being introduced this year. It's possible that Kaye's return is directly connected to these newcomers.

One popular theory, without much evidence behind it, is that Thoros will somehow make his way to Castle Black where he will resurrect Jon Snow. While nearly everyone who has ever watched "Game of Thrones" expects Kit Harington's Lord Commander to return from his grisly fate at the end of Season 5, most expect Melisandre to be behind it.

As of right now, it's unclear what circumstances will bring Kaye's Thoros back into the main fold. All we have now is speculation and theories. We'll know more once "Game of Thrones" returns to HBO this Sunday at 9 p.m. ET.

Follow Brandon Katz at @Great_Katzby.