1. Chyna
Regardless of your opinion of Chyna, there's no denying she pushed the boundaries of what could be achieved by women in WWE. When she first began to wrestle, there was hesitation from some of the male stars who didn't want to be seen being overpowered by a woman, or on the contrary, violent towards a woman; but Chyna's strength and size made hera much better fit in the men's division than the Divas'. She created her first piece of history by becoming the first woman to enter the Royal Rumble match in 1999, and then again in 2000. Eventually Chyna became a full-time fixture of the men's division, having regular sinlges matches with male wrestlers of different size, strength and ability, despite the original skepticism. Later in 1999 she would break more ground by being the only woman to enter a King of the Ring tournament, be named the #1 contender (although she never received a WWE title match), and then later become the Intercontinental champion. As the Divas division grew and improved, Chyna would be 'demoted' to wrestling women, which is regarded as one of the reasons she would become disenchanted with WWE, and retire from wrestling to begin other pursuits *ahem*. Chyna was somewhat of a phenomenon, and it's hard to believe that there'll ever be a woman who could compete full-time in the men's division, not just in our lifetimes, but maybe ever.