In boxing, it is common knowledge that to be the best, you have to beat the best.
The five that make this list certainly did that, as we take a look at the five longest title reigns in boxing history.
Title reign: 11 years, 8 months, 8 days
Joe Louis tops the list for the longest title reign in boxing history, holding the lineal championship for 11 years, eight months and eight days.
Regarded by many as one of the greatest and most influential boxers of all time, Louis successfully defended his title on 25 occasions, a record for all weight classes.
He recorded 52 knockouts, boasting a 66-3 record in his 17-year boxing career.
Title reign: 9 years, 7 months and 6 days
One of boxing's bigger names in recent times, Wladimir Klitschko enters the list in second for his reign as the IBF heavyweight champion.
He defended his championship on 18 occasions, before eventually handing over the belt to Tyson Fury when the 'Gypsy King' defeated him on 28th November 2015.
The Ukrainian fought just once more after his defeat to Fury, losing to Anthony Joshua at Wembley Stadium on 29th April 2017, following just shy of 18 months out of the ring.
Title reign: 7 years, 3 months, 12 days
Larry Holmes won the WBC heavyweight title in 1978, defeating Ken Norton to extended his record to 28-0.
He would then go on to defend his title a record-breaking 16 times before the WBC heavyweight title became the IBF heavyweight title.
A change in the name of the belt brought about an unexpected change in fortunes for Holmes, who would only successfully defend the title three times before losing for the first time ever against Michael Spinks in 1985. The pair would fight again just seven months later, but Holmes was unable to regain the IBF title.
Title reign: 7 years, 2 months, 19 days
Jack Dempsey was an American boxer, who had a 13-year boxing career between 1914 and 1927.
Also known as the "Manassa Mauler", Dempsey became champion in 1919 and wouldn't lose his belt until 1926.
An aggressive boxer who possessed serious power, Dempsey lost just six of 83 bouts, winning 68 and drawing nine.
Title reign: 7 years, 0 months, 9 days
John L. Sullivan, nicknamed the "Boston Strong Boy", is known as the first heavyweight champion of gloved boxing.
John L. Sullivan lost the title on his last ever fight, being knocked out by James J. Corbett on 7th September 1892 in New Orleans.
Defeated just once in 46 bouts, Sullivan was also known for his bare-knuckle boxing ability.