Boxing has long been complicated and dogged by the politics and infighting of the sport’s various sanctioning bodies, especially between the 1970s and about 2000. Numerous world champions were stripped of their title belts for a variety of reasons including drug-test failures. However, most champs lost their titles by refusing to face their sanctioning body’s mandatory challenger.

This list focuses on the top 10 heavyweight champions who were stripped of their title by at least one of the world’s governing bodies such as the WBO, WBA, IBF,IBO and WBC. We’ve also included the NYSAC (New York State Athletic Commission) and the NBA (National Boxing Association) which ruled from the 1920s to the early 1960s. The NYSAC then supported the WBC while the NBA became the WBA. And just remember how confusing boxing can sometimes be with each governing body usually recognizing its own champion.

10. Ray Mercer

Ray Mercer was a solid American heavyweight who fought from 1989 to 2008 with a record of 36-7-1 with 26 Kos. He was also a fine amateur who won the gold medal in the heavyweight division at the 1988 Olympics in Seoul, South Korea. In fact, he went 64-6 in the amateur ranks. Mercer knocked Francesco Damiani out in the ninth round on January 11th, 1991 to win the WBO title. He then stopped Tommy Morrison in the fifth round nine months later in his first defense. However, just a couple of months later on Christmas Eve, Mercer was stripped of the belt because he decided to take on Larry Holmes rather than Michael Moorer who was the WBO’s mandatory challenger. Mercer was a 4/1 favorite to beat the 42-year-old Holmes when they met in February, 1992, but he lost a unanimous decision.

9. Leon Spinks

‘Neon’ Leon Spinks (26-17-3, 9 Kos) made history by beating Muhammad Ali via split decision in February of 1978 in just his eighth pro fight and took home the WBC and WBA Heavyweight Titles for his effort. Spinks was already a household name since he won the light-heavyweight gold medal for the U.S. at the 1976 Olympic Games in Montreal. After beating Ali, Spinks decided to give the people what they wanted, which was a rematch with the former champion. The WBC insisted he fight number-one challenger Ken Norton though and duly stripped their title from Spinks on March 18th 1978. Norton was then forced to take on the new WBC challenger, Larry Holmes, and lost the title in his first fight as champion. And Ali also beat Spinks in their rematch to regain the WBA Crown.

8. Michael Spinks

The Spinks brothers made a lot of boxing history in their time and are also the only siblings to be stripped of a heavyweight title. Michael won gold as a middleweight at the 1976 Olympics and went on to become one of the best light-heavyweight champs in history, retiring at 31-1 with 21 Kos. Spinks challenged IBF Heavyweight Champ Larry Holmes, who was 48-0, and beat him by unanimous decision in March, 1985. Spinks immediately relinquished his undisputed light heavyweight championship after the fight to focus on boxing at heavyweight. He beat Holmes in a rematch and also defended the belt against Steffen Tangstadt. However, he was then stripped of the title in February, 1987 for fighting Gerry Cooney rather than IBF mandatory contender Tony Tucker. Spinks was still recognized by the fans and Ring Magazine as the champ until getting knocked out in the first round by Mike Tyson in Spinks’ final career bout in 1988.

7. Max Schmeling

Germany’s Max Schmeling fought from 1924 to 1948 with a record of 56-10-4 with 40 Kos. He won the vacant NYSAC and NBA Heavyweight Titles in June of 1930 when Jack Sharkey was disqualified in the fourth round. Schmeling defended the NBA Title once, but refused to give Sharkey a rematch. The NYSAC decided to strip their title from Schmeling in 1931 and left it vacant. But Schmeling then decided to give Sharkey a rematch in June of 1932 and the bout was for the NBA Title as well as the vacant NYSAC version. Sharkey took the titles home though after winning a highly-controversial 15-round split decision. Schmeling would never win another heavyweight title other than the European crown. He did go on to knock Joe Louis out in the 12th round in 1936 before Louis was champion. Louis fought Schmeling again in 1938 when the American was the champ, and proceeded to knock him out in the first round.

6. Jack Johnson

One of the most famous early heavyweight champions was notorious American Jack Johnson who fought from 1897 to 1931 with a record of 56-11-8 with 36 Kos. Johnson became the first African/American heavyweight titleholder when he stopped Tommy Burns in the 14th round in 1908. Johnson would make seven official defenses of the title until Jess Willard stopped him in the 26th round of their 1915 bout. But technically, Johnson was stripped of the title in 1909 by England’s National Sporting Club when the champ reneged on an agreement to fight British champion William Hague. The National Sporting Club was the second-most powerful boxing organization at the time and they matched Hague against Sam Langford of Canada for what they considered to be the vacant title. Langford stopped Hague in the fourth round in May, 1909, but never claimed any part of the heavyweight title as he believed Johnson was still the champ.

5. Riddick Bowe

American Riddick ‘Big Daddy’ Bowe was well known by the time he turned pro in 1989 as he fought Lennox Lewis for gold in the super-heavyweight division at the 1988 Olympics. Bowe lost that fight, but his pro career lasted until 2008 with an impressive record of 43-1 with 33 Kos. His lone defeat came at the hands of Evander Holyfield, who beat him by 12-round majority decision in 1993. However, Bowe had decisioned Holyfield a year earlier and would also knock him out in 1995 to avenge his loss. Bowe won the WBC, WBA and IBF Titles in his first win over Holyfield in November, 1992, but just a month later the WBC stripped him of their belt for refusing to fight mandatory challenger Lewis. Bowe then held a press conference and dumped the WBC belt in a garbage can in front of the assembled photographers and Lennox Lewis was declared the organization’s new champ.

4. George Foreman

Big George Foreman (76-5, 68 Kos) was another American heavyweight who won gold as an Olympian. Foreman won the heavyweight title at the 1968 Games in Mexico City and turned pro a year later. He then won the WBC and WBA Heavyweight Titles when he demolished ‘Smokin’ Joe Frazier in the second round in January, 1973. He defended those belts three times until Muhammad Ali stopped him in eight rounds the next year. Foreman retired for a decade in 1977 and made his famous comeback in 1987. He became the oldest man to win a heavyweight crown when he stopped Michael Moorer in the 10th round in June 1993. Foreman was 45 at the time and won the IBF and WBA Titles. The WBA took their title from him though when Foreman decided to fight Axel Schulz instead of top contender Tony Tucker. Foreman beat Schulz by close majority decision, but the IBF then stripped him for refusing to give Schulz a rematch.

3. Mike Tyson

American Mike Tyson made boxing history by becoming the youngest heavyweight champ when he knocked Trevor Berbick out in the first round in 1986. He then won the WBA, IBF and Lineal versions of the Championship soon after. He fought from 1985 to 2005 with a mark of 50-6 including 44 Kos and was one of the most-feared boxers of his era. Tyson was stripped of his WBC Title in 1996 after agreeing to fight former champ Lennox Lewis. The two couldn’t agree on a contract though and Lewis ended up suing. The two sides came to a legal settlement, but Tyson lost his WBC belt in the agreement. Tyson would go on to regain the WBC and WBA Belts and eventually fought Lewis in 2002 for the WBC, IBF and IBO Titles, but was knocked out in the eighth round.

2. Lennox Lewis

British-born Lennox Lewis fought for Canada at the 1988 Olympics and beat future World Heavyweight Champ Riddick Bowe for the gold medal. He’d turn pro in 1989 and retire in 2003 with a record of 41-2-1 with 32 Kos. Lewis surprised many people with his talents and is rightly recognized as one of boxing’s greatest heavyweight champions. At one time he held the WBA, WBC, IBF and IBO Belts. He defended his titles numerous times and still held the WBC and IBO Titles when he hung up his gloves. The WBA stripped him of their championship in 2000 when the organization was sued by number-one contender John Ruiz and the champ decided to fight Michael Grant instead. Lewis also lost his IBF Belt in December of 2002 when he decided to bypass their top contender Chris Byrd and fought Mike Tyson several months later.

1. Muhammad Ali

‘The Greatest,’ Muhammad Ali, was actually stripped of a heavyweight title on two occasions. The light heavyweight winner of the 1960 Olympics in Rome went 56-5 as a pro with 37 Kos from 1960 to 1981 and is as legendary as a person as he is a boxer. Ali was just 22 when he beat Sonny Liston for the WBA, WBC and Lineal Titles in 1964. However, the WBA took their title from him when Ali decided to give Liston an immediate rematch. Ali would defend his other titles nine times and also regained the WBA Belt in February, 1967 when he beat Ernie Terrell. Then just two months later, Ali was stripped of all his titles when he refused induction into the U.S. Army. Ali was convicted of draft evasion, but it was overturned in 1971. He would go on to become a three-time heavyweight champ and the most recognizable man on the planet.