Alistair Cees Overeem (Dutch pronunciation: , English: /ˈoʊvəriːm/;) is an English-born Dutch mixed martial artist and former kickboxer. He is a former Strikeforce Heavyweight Champion, DREAM Interim Heavyweight Champion, K-1 World Grand Prix Champion, and is one of only two fighters to hold world titles in both MMA and K-1 kickboxing at the same time. As of 9 December 2017, he is #2 in the official UFC heavyweight rankings. He holds notable victories over six former UFC champions: Andrei Arlovski, Frank Mir, Brock Lesnar, Junior dos Santos, two victories over Vitor Belfort, along with two victories over Fabrício Werdum.
Overeem was born in Hounslow, England to a Jamaican father and a Dutch mother. When he was six years old, his parents divorced and he moved with his mother and older brother to the Netherlands. As a child, Overeem competed in judo, track and field and basketball. At the age of 15, Overeem's older brother Valentijn took him to Chris Dolman's MMA gym to learn to defend himself. Alistair initially did not like the sport, but he dedicated fully to it after meeting Bas Rutten and Joop Kasteel.