A few years back WWE.com posted a blog titled "17 Superstars you didn't know competed in ECW": https://www.wwe.com/classics/ecw/17-obscure-ecw-superstars
Don Muraco, Scott Hall, Arn Anderson, Bobby Eaton, and many other names - including several WWE Hall of Fame members - are on this list.
The link above has several video clips from Eastern Championship Wrestling and Extreme Championship Wrestling (collectively "ECW") showing these additional names:
Konnan, Doink The Clown, Marty Jannetty, Nkolai Volkoff, Jim "The Anvil" Neidhart, Jake "The Snake" Roberts, Rick & Scott Steiner, King Kong Bundy, Stan "The Lariat" Hansen, Road Warrior Hawk, and Lita (in ECW known as both Angelica as well as Miss Congeniality). Each name has some history about the wrestler
This playlist organizes the videos better than in the original post along with a couple of additional videos:
https://www.wwe.com/videos/playlists/wrestlers-you-never-knew-competed-in-ecw