Some people are making some odd choices here. Moolah? Great woman. Biggest impact on the WWE? I don't think so. Do you see female wrestlers like Moolah anymore? No way. Remember, we aren't talking about the best female wrestler the WWE has had, or even the best female employee the WWE has. We're talking about who has had the biggest impact.
Now, with the exceptions of Linda and Stephanie McMahon, I think it's obvious that no one has had a larger impact on the WWE than Sunny and Sable. The two of them debuted in the WWF just around the same time, really at the perfect time. Attitude was just starting, and having attractive women come out to the ring really was a pretty new idea if you can get your head around that concept. Seriously, did you see those old valets from the 80s? Beastly. Don't even get me started on the actual wrestlers. Sunny and Sable came around at the perfect time, and became massively popular. Sunny was there first, but Sable took off, probably more than any other woman in WWE history. Her issue of Playboy was one of the highest selling in Playboy's history, she was HUUUUUUUUUUUGELY over with the fans.
Sable would probably have to be my choice here for the biggest impact, because she was the spark that lead to Vince McMahon realizing that he could make a shit load of money off of a beautiful woman. Before the rise of Sable, the woman's division in the WWE was a sad, sad joke for many years. It was defended what, five times in the WWE from the late 80s to the mid 90s? There was very little if any TV time given to female wrestlers. Then along came Sable, and changed everything. Seriously, the WWE had female wrestlers on both Raw and Smackdown, and commits atleast one segment/match per show to them, and has been doing it for a decade now. That's unheard of in the WWE's history, where the women's division had long been miniscule at best, if it even existed.
Sable obviously isn't one of the best female workers, but the impact she had on the WWE and Vince was without a doubt the largest. Without Sable, we don't have two Women's titles in thet WWE right now, simple as that. She awoke Vince to the realization that the "diva's" could make him some serious fuckin' cash.