Three-time WWE world champion Bray Wyatt has died at the age of 36.
The wrestler had been dealing with an undisclosed health issue that had kept him out of the ring since February, but his death was characterised as sudden by his family.
The news was announced by WWE content officer Triple H, who posted on social media that Wyatt, real name Windham Rotunda, had "unexpectedly passed".
Dwayne Johnson, aka The Rock, was among those paying tribute to the star.
Writing on X, formerly Twitter, Johnson said he was "heartbroken" and had "always had tremendous respect and love" for the wrestler.
"Loved his presence, promos, in ring work and connection with @WWE universe," he wrote. "Very unique, cool and rare character, which is hard to create in our crazy world of pro wrestling."
WWE commentator Mick Foley added: "I thought so highly of Bray Wyatt... He was a true visionary; one of the most compelling presences that wrestling has ever seen."
Rotunda came from a family of wrestlers, including his grandfather Blackjack Mulligan, his father Mike Rotunda and his younger brother Bo Dallas.
Born in Brooksville, Florida on 23 May, 1987, Wyatt was a state wrestling champion in high school and earned a football scholarship to Troy University.
However, he left his course before graduating to become a professional wrestler, making his professional debut in 2009.
He fought under several names including Husky Harris, Alex Rotunda, Duke Rotundo and The Fiend.
As Bray Wyatt, he portrayed the villainous leader of a cult faction named The Wyatt family with Erick Rowan, Braun Strowman, and the late Luke Harper (aka Brodie Lee).
After being released from WWE in 2021, he made a long-awaited comeback at the pay-per-view Extreme Rules event last October, where he debuted a new version of his character.
He had recently missed several months due to illness but was close to returning to the WWE before his death, according to Wrestling News.
Triple H, real name Paul Levesque, said he had been informed of Rotunda's death by his father.
"Just received a call from WWE Hall of Famer Mike Rotunda who informed us of the tragic news that our WWE family member for life Windham Rotunda - also known as Bray Wyatt - unexpectedly passed earlier today," he wrote.
"Our thoughts are with his family and we ask that everyone respect their privacy at this time."
Wrestling reporter Sean Ross Sapp later said that the 36-year-old had died of a heart attack, after a brush with Covid that exacerbated existing heart conditions.
"There was a lot of positive progress towards a return and his recovery," he said. "Unfortunately today he suffered a heart attack and passed away."
Wyatt is survived by his fiancee and former WWE ring announcer Joseann Offerman, their four children, brother Bo Dallas (Taylor Rotunda), and sister Mika.