1. Holly Holm
A rare case, Holm scaled the heights in both boxing and MMA and has the titles to prove it. She was a three-weight world champion as a boxer, competing 38 times in total, then knocked out Ronda Rousey in 2015 to win the UFC bantamweight crown.
2. Chris Lytle
A firefighter by trade, Lytle was one of the UFC’s most popular fighters of all time, yet also boxed 15 times as a pro, winning something called the Indiana Boxing Association light-heavyweight title in 2003.
3. Marcus Davis
Southpaw Davis was known as ‘The Irish Hand Grenade’ and competed 20 times as a po boxer, mainly on the Boston circuit, before making the move to MMA in 2003. He later competed on The Ultimate Fighter and fought numerous times in the UFC.
4. Fabio Maldonado
Brazilian Maldonado has run boxing and MMA careers concurrently and done well in both. As a mixed martial artist, he won five times in the UFC, while as a boxer he has managed to become an opponent for the likes of Michael Hunter and Oscar Rivas.
5. Ryan Ford
Recently seen succumbing to Joshua Buatsi in London, Ford has competed 21 times as a boxer and 27 times in MMA. He has won minor titles in both and fought plenty of the top fighters in the world.
6. Heather Hardy
Hardy, like Holm, has been able to make a name for herself in more than just one fighting discipline. As a boxer, she has had 24 fights and won a WBO featherweight title, while in MMA she is 2-2 and a star with Bellator.
7. Eric ‘Butterbean’ Esch
Esch, also known as Butterbean, also known as ‘The King of the Four-Rounders’, competed 91 times as a pro boxer and 28 times in MMA. He scored plenty of eye-catching knockouts in both disciplines and was popular wherever he went.
8. Ray Mercer
Mercer, a heavy-handed former WBO heavyweight champion, had just the one MMA fight but caused quite a scene when he knocked out Tim Sylvia, a former UFC heavyweight champion, inside nine seconds back in 1999.
9. James Toney
Toney, a 92-fight former champion in multiple weights, made the terrible decision to move to MMA in 2010 and was duly taught a lesson by Randy Couture, a UFC titleholder at heavyweight and light-heavyweight.
10. Art Jimmerson
Jimmerson was the one who started it all. Back in November 1993, Jimmerson, a light-heavyweight boxer, competed against Royce Gracie at UFC 1 and did so with a boxing glove on his left hand. He was submitted in the first round.