“If you are not fighting and not training, it does have an effect on you no matter who you are.”

British professional boxer

Callum John Smith is a British professional boxer. He has held the WBO interim light-heavyweight title since 2025, and earlier was a world champion at super-middleweight, with the WBA and Ring magazine titles from 2018 to 2020. He won both of those belts in the World Boxing Super Series, where he also claimed the Muhammad Ali Trophy. At regional level, he held the British and European super-middleweight titles between 2015 and 2017. As an amateur, he took silver at the 2010 Commonwealth Games. He is the youngest of the Smith brothers, alongside Paul, Stephen, and Liam, all of whom are professional boxers.