Julianna Nicole Peña[1] (born August 19, 1989) is an American professional mixed martial artist who competes in the women's Bantamweight division of the Ultimate Fighting Championship (UFC), where she is the two-time and current UFC Women's Bantamweight Champion.

[8] In order to lose weight and channel aggression in her early adulthood, she enrolled in a cardio kickboxing class and subsequently transitioned to mixed martial arts.

[9] She won four consecutive fights but suffered her first defeat in April 2012 to future fellow The Ultimate Fighter 18 cast member Sarah Moras in a 140-pound catchweight bout.

[10] The fight took place just two months and one week after Peña was involved in an accident with a drunk driver while walking in downtown Spokane in which she was knocked unconscious and suffered a broken nose.

[13][14] During the first tournament fight in the house, Peña faced veteran and top-ten ranked Shayna Baszler.

The fight went to the ground, where Peña was able to achieve back mount and won via rear naked choke for perhaps the biggest upset victory of the season.

She suffered the injury while grappling in training, ultimately damaging, among other aspects, her ACL, MCL, LCL and meniscus.

Despite the severity of the injury, doctors assured Peña that her right knee would return to full strength following surgery and rehabilitation.

[44] After a dominant round one from Nunes, Peña came back in the second to win the bout and championship by rear-naked choke submission in what is regarded as one of the biggest upsets in UFC history.

[45][46][47][48] On February 5, 2022, it was announced that Peña and Nunes would be the coaches for The Ultimate Fighter 30 on ESPN+, which would feature contestants from the heavyweight and women's flyweight divisions.

[52] However, on May 2, 2023, it was announced that Peña pulled out of the bout due to broken ribs she sustained during training camp.

Irene Aldana, who was scheduled to headline UFC Fight Night: Dern vs. Hill, was subsequently chosen to replace her.

[56] Peña was featured in the award-winning mixed martial arts documentary Fight Life, the film is directed by James Z. Feng and was released in 2012.

[57] Peña is an announcer, along with Max Bretos, for Combate Americas' English language broadcast on DAZN.