Casey “King”O'Neill

Casey O’Neill is a Scotland-born, Australian-raised mixed martial artist who competes in the UFC women’s flyweight division under the nickname “King.” The UFC lists her as an active athlete, born in Irvine, Scotland, on October 7, 1997. She is listed at 5 feet 6 inches tall with a 69-inch reach and trains at Bangtao Muay Thai. O’Neill began kickboxing as a child alongside her father and later added Brazilian jiu-jitsu and MMA to her training.

O’Neill turned professional in 2019 and made her UFC debut on February 20, 2021, stopping Shana Dobson. Her early UFC run included a rear-naked-choke submission of Lara Procopio and a stoppage of Antonina Shevchenko. Before reaching the UFC, she held two regional strawweight championships in Australia. Her official UFC profile describes a brown belt in jiu-jitsu, while her stated favorite striking technique is boxing and her favorite grappling approach is joint locks. She did not attend college, choosing to commit fully to fighting before finishing high school.