To prep for her first foray to the Octagon, O’Neill found a home in Vegas at Xtreme Couture and the UFC Performance Institute. While the move wasn’t necessarily in the plans – she intends to move back to Tiger Muay Thai in Thailand at some point – as mentioned before, the 23-year-old isn’t a stranger to moving somewhere new. 

“I like to think I thrive under situations like that,” O’Neill said. “I’ve always done the uncomfortable in order to make myself comfortable in those situations, so for me, this one wasn’t as bad as the first two had been. I guess it just gets to a point where you’re like, ‘OK, my situation, I’ve outgrown it.’

After spending the first part of her life in Scotland, O’Neill’s family moved to the Gold Coast of Australia, where her father Cam O’Neill, a former professional kickboxer, started an MMA promotion. It wasn’t long before Casey was begging her dad to let her start training. 

When she turned eight years old, Cam allowed Casey to start kickboxing, and when she would help her dad at events, she would press him about letting her fight. 

“At first, he was hesitant,” she said. “He was like, ‘No, I don’t want my daughter doing it.’ It was really rare for females to be fighters back then as well, so he was like, ‘You’re not going to do it.’ I was 15 when he was finally like, ‘All right, you train every day. I’ll let you have a crack at it.’ And now, he’s my biggest supporter. He’s missed one fight in my whole life. That was the last fight. He loves it. He’s all-in on me doing this, so he supports me all the way in coming here and doing everything I’m doing.”