#1 Ronda Rousey

Last, but definitely not least, comes The Baddest Woman on the Planet.
Ronda Rousey is a revolutionary figure in the MMA world, as she had broken down barriers for many female fighters all over the world. She was the biggest draw for the UFC when she was competing in fights, as she had dominated as the UFC Bantamweight Champion, and she brought many new viewers to the UFC brand with a win-loss record of 12-2. Rousey was inducted into the UFC Hall of Fame in 2018.
At one point, she had never lost a match before her undefeated streak was broken by Holly Holm at UFC 193 during Round 2 in 59 seconds on November 15, 2015. Rousey had also lost to Amanda Nunes via TKO in UFC 207 on December 30th, 2016 during Round 1 at 48 seconds.
These losses broke Rousey's mystique, but it also broke Rousey to the point where she had gone through depression. However, Rousey is the epitome of the phrase "what doesn't kill you makes you stronger" as she is now competing in the WWE as the current Raw Women's Champion with a Wrestlemania main event in store for her alongside Becky Lynch.
There is no denying that Rousey is the most decorated individual in terms of having an MMA background due to her success with selling PPVs, winning matches as well as making it in the WWE just like Lesnar did.
Did a WWE Hall of Famer predict John Cena's heelish ways long ago? More details HERE.