Ray Mercer declared the winner over Tim Sylvia in an MMA bout.
We've covered Muhammad Ali's venture into proto-MMA, Judo Gene LeBell vs Milo Savage in the 1960s, and Art Jimmerson at UFC 1 plus cruiserweight champ James Warring and Melton Bowen in the early MMA PPV days in the states, plus a review of boxers like Jeremy Williams, Marcus Davis and Chris Lytle who have really adapted to the game, but there have been a few more and I didn't want BE readers to miss a single one.
Note that many of these fights took place in Japan in the proto-MMA era when their worked pro wrestling promotions were moving closer and closer to shoot fights and true MMA. Most of the fighters involved were proteges of Antonio Inoki. Learn more about Japanese Proto MMA here.
Dave Meltzer has a solid round-up. New info to BE readers is:
Matthew Saad Muhammad: A decade after holding the WBC light heavyweight championship, Muhammad, on May 8, 1992, in Yokohama, Japan, faced Kiyoshi Tamura, at the time a popular pro wrestler. Tamura exploded with a takedown and finished Muhammad with a choke in 34 seconds. Tamura would later go on to a solid career as an MMA fighter with wins over Maurice Smith, Renzo Gracie, Minowa-man, Kazushi Sakuraba, Masakatsu Funaki, Pat Miletich and Jeremy Horn and a draw with a prime Frank Shamrock.
Imamu Mayfield: The former IBF cruiserweight champion fought Japanese wrestler Kazuyuki Fujita on December 31, 2003. To make things more fair for the boxer, the rules were set up so Fujita would get only 20 seconds on the ground before he was stood up. Mayfield never got in a good punch, and was repeatedly taken down by Fujita. Fujita, never a submission specialist, would go for moves but couldn't get them in 20 seconds. Finally, Fujita grabbed an arm triangle choke standing, where time wasn't working against him, and Mayfield submitted at 2:15 of the second round.
Ray Mercer: The former Olympic gold medalist and WBO heavyweight champion, Mercer was the biggest-name heavyweight boxer up to this point to try MMA, although he didn't do it until he was well past his prime. Mercer was 46 when he fought Kimbo Slice on June 23, 2007, under MMA rules in an Atlantic City match that the New Jersey Athletic Control Board labeled as an exhibition. Slice choked Mercer out with a guillotine in 2:00 in what was also Slice's first foray into MMA. Mercer knocked out hideously out-of-shape former UFC heavyweight champion Tim Sylvia in nine seconds on June 13, 2009, in Birmingham.
MMA Scraps has more on Tamura vs Saad Muhammad.
Trevor Berbick (August 1, 1954 - October 28, 2006) was a Jamaican - Canadian heavyweight boxer and champion who fought as a professional from 1976 until 2000. He was the victim of a homicide near his hometown of Norwich, Jamaica. Berbick briefly held theWBC heavyweight title in 1986, before losing it to Mike Tyson on November 22, 1986, by a TKO in the second round. He was the last man to fight Muhammad Ali, winning a 10-round unanimous decision in Nassau, Bahamas on December 11, 1981.
In 1991, he went to the UWFI in Japan to fight Nobuhiko Takada in a "boxer vs. wrestler" bout. Berbick claimed that he had been double-crossed and that he had expected the fight to be like American kickboxing, but it turned out that the rules allowed Takada to kick Berbick below the belt. Berbick refused to mount any offense, instead repeatedly complaining to the referee as Takada kicked him repeatedly in the legs. Takada claimed victory by default when Berbick exited the ring.
And MMA Torch has a fine feature on some more boxers who've dabbled in MMA, we'll cover that in the full entry, plus videos from the fights.
From MMA Torch:
Frans Botha, a heavyweight contender in the late-90s, is best known for out-boxing a post-prime Mike Tyson for four rounds in 1999 before getting knocked out in the fifth. The next year, heavyweight champion Lennox Lewis demolished Botha in two rounds. "The White Buffalo" left boxing in 2002 (with a 44-4-2 record) for a career in K-1. His stint as a kickboxer was largely unsuccessful, the notable exception being a stoppage victory over Jerome Le Banner. On December 31, 2004, the then 36-year-old Botha engaged in his first and, to date, only MMA fight. His opponent was debuting judo player and future UFC middleweight contender Yoshihrio Akiyama. Akiyama defeated Botha by armbar submission in under two minutes. Botha has since returned to boxing, most recently suffering a loss to the ancient Evander Holyfield.
Vaulin was an accomplished amateur boxer for the Soviet Union. As the USSR disintegrated, Vaulin came to America, debuting in 1990 on a card televised nationally by the USA Network. Fighting as a heavyweight, the prospect Vaulin progressed to 9-0 before being upset by the "suspect" John Sargent. Vaulin's loss was marked by the ignoble move of quitting on his feet in the eighth round of a ten rounder without having been knocked down or even having endured any serious punishment. After the Sargent loss, Vaulin's star fell, and he would continue boxing through 1992 without enjoying any particular success or notoriety. Along the way, he compiled a win-loss ledger of 13-3. In 1997, at age 33, Vaulin competed at UFC 14. Perhaps stung by the criticism of the lack of grit he displayed against Sargent, Vaulin fought with heart against jiu-jitsu player Joe Moreira. Ultimately, though, Moreira took the unanimous decision.
Nishijima, a Japanese cruiserweight, campaigned primarily in the United States. Though his record stood at 24-2-1, the fact that he failed to make a dent in America's notoriously weak cruiserweight boxing scene says something about his abilities. In 2006, four years after he was stopped in two rounds by journeyman Cecil McKenzie, the 32-year old Nishijima entered MMA. He competed against the much larger Mark Hunt at Pride 31, losing by knock out in the third round of an exciting slugfest. The loss was the most competitive fight of Nishijima's MMA career: he lost each of his remaining four bouts more definitively than he did his match with Hunt. Nishijima most recently popped up in combat sports in 2009, losing twice that year in K-1.
Here's Tamura vs Saad Muhammad:
And here's Nobuhiko Takada vs Trevor Berbick 1991.12.22 UWF international