Callum John Smith (born 23 April 1990) is an English professional boxer. He held the World Boxing Association (WBA) (Super version) and Ring magazine super-middleweight titles from 2018 to 2020. At regional level, he held the British and European super-middleweight titles between 2015 and 2017. In 2018 he won the World Boxing Super Series super-middleweight tournament, winning the Muhammad Ali trophy in the process. He is the youngest of the Smith brothers—Paul, Stephen, and Liam—all of whom are professional boxers.