Neil Fingleton, the remarkably tall actor who was best known for portraying Mag the Mighty on HBO's Game of Thrones, died Saturday due to heart failure, TMZ reports. He was 36.

The 7-foot-7 British thesp had a brief but still memorable career on the small and big screens, earning his first credit for a cameo role in X-Men: First Class and subsequently earning parts in films like 47 Ronin, Jupiter Ascending, and Avengers: Age of Ultron.

In his short-lived Game of Thrones role, Fingleton played Mag the Mighty, aka Mar Tun Doh Weg, in the series' fourth season, a character that was a member of Mance Rayder's wildling army and helped the free-folk breach the wall during the Battle of Castle Black.

Fingleton also portrayed Fisher King on the BBC America's Doctor Who in 2015.

Fingleton was a collegiate and professional basketball player before taking up a screen career and held the distinction of being the United Kingdom's tallest man during his lifetime.

Very sad to hear of the tragic passing of Neil Fingleton.
He followed his dreams.
Rest in peace.

— Ian Whyte (@Ian_Whyte) February 26, 2017

Extremely sadden to learn that #NeilFingleton has passed away, thoughts go with his family and friends in this sad time :( #ripneilfingleton

— Matthew Rose (@rose962_matt) February 25, 2017

Gutted and devastated, RIP Neil Fingleton mate!! - feeling upset

— Peter Mann (@petermannwriter) February 25, 2017