American professional wrestler and WWE superstar Bray Wyatt has died from heart attack after several months battling an undisclosed life-threatening illness.

“WWE is saddened to learn that Windham Rotunda, also known as Bray Wyatt, passed away on Thursday, Aug. 24, at age 36,” the professional wrestling professional announced  Thursday. “WWE extends its condolences to Rotunda’s family, friends and fans.”

He was 36.

Wyatt, whose real name was Windham Rotunda, was known for his gimmick as ‘The Fiend’, a demonic masked sinister figure with ability to control darkness, tormented the promotion for a period of time.

Wyatt had been sidelined from the wrestling ring since February as the former WWE Championship and WWE Universal Championship winner battled a life-threatening illness.

Tributes have been pouring in from the wrestling community since the announcement of Wyatt’s death.

Former WWE superstar Dwayne ‘The Rock’ Johnson said, “I’m heartbroken over the news of Bray Wyatt’s passing. Always had tremendous respect and love for him and the Rotunda family. Loved his presence, promos, in ring work and connection with @wwe universe.”

“This is awful news, just terribly sad for his family, friends and fans. I thought so highly of Bray Wyatt, and was so flattered when he started using the mandible claw for his finisher. He was a true visionary; one of the most compelling presences that wrestling has ever seen,” said former wrestler Mick Foley.

In his tribute, WWE Hall of Famer Ric Flair, tweeted, “When Your Great Friend And Someone Your Son’s Age Dies Within 2 Days, It Really Makes Me Reflect & Think About Life! Don’t Take Any Second For Granted! Rest In Peace Terry Funk & Bray Wyatt!.”