English actor and basketball player Neil Fingleton has died. Named Britain’s tallest man in 2007, Fingleton turned professional actor with roles in 2011’s X-Men: First Class and in 2013’s 47 Ronin. In what is his best-known turn, he played Mag the Mighty in HBO’s Game Of Thrones. A rep for the actor could not confirm how Fingleton died, although multiple reports say he suffered heart failure on Saturday. He was 36.

A statement posted to the Tall Persons Club group Facebook page on Sunday said, “Sadly it has come to our attention that Neil Fingleton Britain’s Tallest man passed away on Saturday… Our thoughts and condolences go out to his family.”

Born in Durham, England in 1980, Fingleton spent eight years in high school and college in the U.S. He played for the ABA’s Boston Frenzy during the 2004-2005 season and later went on to play professionally in Greece, Italy and Spain.

In a 2007 Guinness Book of World Records posting, the 7 ft 7.56 inch Fingleton said he was concentrating on acting after his basketball days and “trying to move to LA soon to jump in with both feet so to speak.”

His other credits include Jupiter Ascending, Avengers: Age Of Ultron and Doctor Who, in which he played villain The Fisher King.

Game Of Thrones’ Ian Whyte remembered Fingleton today:

A rep for Fingleton told Deadline he was “a great actor, always professional and a down to earth kind of guy and it was a pleasure to have worked with him. We know he will be sorely missed by all who knew him.”