Jan Maciej Błachowicz (Polish: ; born 24 February 1983) is a Polish professional mixed martial artist. He currently competes in the Light Heavyweight division for the Ultimate Fighting Championship (UFC), where he is a former UFC Light Heavyweight Champion. A professional since 2007, he also competed for KSW and is the former KSW Light Heavyweight Champion. He is the second Polish champion in UFC history, after Joanna Jędrzejczyk, and the first male Polish champion. As of August 1, 2023, he is #4 in the UFC light heavyweight rankings.