He was not as well known as many Superstars because his wrestling career was short and he spent a long time working in the backstage office, but to those who followed WWF/E for a long time, you may have seen him as one of Vince McMahon's Stooges AKA Patterson and Brisco who appeared on camera from time to time (often with a retired Sgt. Slaughter).
Most notably, he was WWF's first Intercontinental Champion, it was the second-tier singles title belt behind the World Championship.
Patterson also is credited with inventing the Royal Rumble. It's like a Battle Royal but instead of all 30 men starting in the ring, you start with two in the ring and the other 28 enter at one-minute or ninety-second intervals. This created more storytelling possibilities. If you were the first man to enter, you had to beat 29 other guys in a match that lasts an hour or more. If you were the last guy in, you only had to beat a few guys and last maybe five mintues. So in the weeks leading up to the event they would draw lots for placements in the match, they might hold a mini-tournament to get the coveted #30 spot, etc. The Royal Rumble match became the basis for one of WWE's "big four" annual wrestling events, the others being Wrestlemania, Survivor Series and Summer Slam.
The article above mentions Pat being the first openly gay pro wrestler, I'm not sure that's true, even in the WWE. It also says he publicly came out in 2014 but I think it was a well known fact since the 1980s at least.
I wouldn't call his wrestling career short. He started wrestling in 1958 and retired in 1985. His career was winding down when wrestling started to go national. In the territory days, he wrestled mostly on the west coast during the '60s and '70s.
As for being the first openly gay wrestler, I don't think the fans knew, but I'm sure the promoters and other wrestlers knew.