Former UFC heavyweight champion Brock Lesnar has retired, the mixed martial arts promotion confirmed on Wednesday.
The 39-year-old returned from a four-year MMA absence to beat Mark Hunt at UFC 200 last July, but the result was overturned after he failed two doping tests.
Lesnar fought for the UFC just eight times, but he became one of the biggest pay-per-view stars in its history during his brief run.
The decision doesn't affect Lesnar's professional wrestling career, and he is scheduled to perform for the WWE at WrestleMania in Orlando on 2 April.
Lesnar made a guaranteed $2.5m (£2.01m) purse for his victory over Hunt last year, but failed a drug test taken before the bout and another on fight night.
He was subsequently suspended from competition for a year by the US Anti-Doping Agency, which administers the UFC's doping policy.
Lesnar's decision to retire means he has been removed from USADA's drug-testing pool, which monitors the fighters year-round.
If he decides to return to competition, he would have to serve the remaining five months of his suspension.
Lesnar won the UFC heavyweight title in just his third fight for the promotion, beating Randy Couture in November 2008.
He defended the belt twice before losing it to Cain Velasquez in October 2010, and he lost to Alistair Overeem in December 2011 in his final fight before his 2016 comeback.
He also endured serious health problems that curtailed his MMA fighting prime, including a bout of diverticulitis.