Known for his grills, people forget how good "Big George" was with his fists. His famous win against Michael Moorer in 1991 saw him crowned the oldest heavyweight champion in history at 45.
The Hall of Fame boxer became the first fighter to earn $100million in the sport and is remembered for his Fabulous Four rivalry with Duran, Hagler and Hearns.
Holyfield remains the only fighter to have unified the cruiserweight division before moving up to become undisputed heavyweight champion.
Boxing's first billion-dollar fighter is regarded as one of the greatest fighters of all time and in 2017, he surpassed Rocky Marciano's record to move 50-0 before retiring for a third time.
In two heavyweight world title reigns, and a total of 11 years as champion, Klitschko got inducted into the Hall of Fame in 2020 for his dominance in the 2000s.
Boxer, entertainer, activist and philanthropist - Ali is crowned as "The Greatest" to have laced a pair of gloves but his work outside the ring was just as incredible as his achievements in the ring.
Having beat everyone on his record, and avenging both defeats on his record, Lewis is ranked as one of the best heavyweights of all-time and the last undisputed champion of the division.
