Former UFC title challenger and legendary knockout artist Anthony Johnson reportedly has died. He was 38.

News of Johnson’s death began circulating Sunday with social media postings by many prominent figures in the MMA community. His manager, Ali Abdelaziz, did not immediately return a message to MMA Junkie to confirm the news.

According to Yahoo!Sports, Johnson died from organ failure due to non-Hodgkin’s lymphoma and hemophagocytic lymphohistiocytosis, a rare disorder of the immune system.

Nicknamed “Rumble” when inside the cage, Johnson (23-6) twice fought for the UFC light heavyweight championship against Daniel Cormier in May 2015 and April 2017. He lost both fights by submission. The latter matchup wound up as his retirement bout from UFC competition. He walked from fighting for more than four years.

Johnson returned to MMA under the Bellator banner in May 2021 and earned a knockout victory over Jose Augusto. He was scheduled to fight in the organization’s 205-pound tournament, but withdrew due to an illness that he largely kept private.

In January, Bellator president Scott Coker confirmed to MMA Junkie that Johnson was dealing with health issues and his timeline to return to fighting was unknown.

“Without getting too much into his medical condition, he’s got to worry just about being healthy first,” Coker said. “He’s got to heal up and get healthy because there’s so much more in life than just fighting. I want him to have a long, healthy life, and that’s the most important thing.”

During his time in the UFC, Johnson amassed a 13-5 record. All but two of those wins came by knockout. His list of notable victories includes a 13-second finish of former UFC champ Glover Teixeira, as well as wins over Alexander Gustafsson, Phil Davis, Andrei Arlovski and Dan Hardy.

After news of Johnson’s death surfaced, the MMA community at large posted on social media with memories and reactions. See some of those posts below.