Stephan Bonnar cause of death: Coroner report reveals what killed UFC legend

Stephan Bonnar's cause of death has been revealed and it's not what we initially thought.

Stephan Bonnar was one half of the fight which many credit as putting the UFC on the map. Though his career didn't end in the glory which it started, he was still highly respected and celebrated by fans.

When it was revealed that the 45-year-old former fighter had died in December 2022, the MMA community rallied to share their thoughts and prayers for Bonnar and his family.

Now, months removed, his official cause of death has been revealed.

According to MMA Fighting, who confirmed his cause of death with the Clark County coroner, he died of “Fentanyl, Parafluorofentanyl and Mitragynine intoxication” and according to the outlet, "the coroner’s office declined to provide additional details on Bonnar’s death, citing medical privacy laws."

At the time of his death, many had believed it was due to “presumed heart complications.”

Bonnar had a history of substance abuse, which he talked about publicly and was seen more than once on tape seemingly under the influence. At one time he was stopped driving "90 mph with unsafe lane changes" and was charged with a DUI after bystanders stopped his car and were holding him until police arrive.

Another incident, shortly before his death saw Bonnar outside of a hospital throwing a fit after being refused pain medication.

The UFC hosted a memorial service for Bonnar after his death that was attended by several fighters, UFC employees and Bonnar's friends and family.