Anthony 'Rumble' Johnson, a former mixed martial arts competitor who fought under the UFC and Bellator banners, died on Sunday (Nov 13) at age 38, Bellator announced on social media.
According to Yahoo Sports, Johnson was diagnosed more than a year ago with non-Hodgkin lymphoma and Hemophagocytic lymphohistiocytosis, a rare immune system disorder.
Bellator tweeted that the organisation "is devastated by his untimely passing, and we send our condolences to his family and friends during this difficult time".
Johnson compiled a 23-6 MMA record with 17 victories by knockout.
He fought in the UFC from 2007-12 and 2014-17, rising to become the No. 1 ranked challenger in the light heavyweight division.
Johnson lost a fight for the vacant UFC light heavyweight title to Daniel Cormier in May 2015, then again fell to Cormier for the light heavyweight championship in April 2017.
After the latter fight, he stepped away from MMA before returning to action at Bellator 258 in May 2021, where he knocked out Jose Augusto Azevedo in the second round of what was billed as a light heavyweight quarter-final match.
He later withdrew from the competition due to illness and did not fight again.
Former UFC welterweight champion Kamaru Usman told Yahoo Sports that Johnson kept quiet about his illness.
Usman said of Johnson's MMA career: "He had the feet of a welterweight and the power of a heavyweight, and he was able to transfer that throughout his career. He was truly special and gifted, and he didn't really have to try hard.
"He felt he was working hard, but there were levels he didn't go to, maybe didn't want to go to.
"He was natural. I admired that so much. He made it look easy. He'd hit a guy and the guy would just crumble. I mean, I worked so hard and put this time in, and I'd wind up and hit this guy with everything, and he'd be standing there.
"Rumble was a different calibre than the rest of us."