Mastodon rocker Bill Kelliher fell asleep while filming his cameo for 'Game of Thrones'.

Bill Kelliher of Mastodon

Bill Kelliher of Mastodon

The guitarist has revealed he was so exhausted that he dozed off after being told to "play dead" when he and his bandmates Brent Hinds, Troy Sanders, Brann Dailor and Eric Saner filmed their guest slot for the HBO medieval fantasy drama.

He said: "There was a lot of playing dead which contrary to popular belief is not that easy to do. I actually fell asleep, laying down on the ground with my battle axe by the water because I was so jet-lagged."

Bill spoke about how he and his metal band ended up getting involved with the much-loved show after they met members of the cast and crew at the music festival Sonisphere last year.

He told British Metal Hammer magazine: "It just so happened that we were starting a tour and they were shooting a scene in Belfast the day before. So the stars aligned and we were able to fly in a day early, quickly get there and jump into a scene."

The 'Once More 'Round The Sun' hitmakers also claimed many of the smaller actors on 'GoT' - which stars Kit Harrington, Emilia Clarke and Maisie Williams - were big fans of theirs.

Bill added: "All the extras on the the show look like our crowd, our target audience - big hairy dudes with giant beards and tattoos. Every single one of them came over and said, 'Hey, how are you doing? We love your band'. It was amazing."