Hulk Hogan, obviously. And I'm anything but a Hogan mark.
He had a huge impact in two different companies - taking the WWF mainstream and then being a major part of one of the greatest angles of all time with the NWO, which helped WCW beat the WWF two years in a row - no other wrestler has done that. He's also someone (similar to someone like Muhammad Ali or Mike Tyson for boxing) that almost everyone knows the name of, even if they're not a fan of wrestling.