WWE.com has posted an article that looks at several big names in wrestling that actually did appear in WWE for a very brief moment in time.
These include Crowbar, The Public Enemy, Baron Von Raschke, Great Sasuke, Kevin Von Erich, Kevin Sullivan, KroniK, Tony Schiavone, The Fabulous Freebirds, Tiger Mask, The Rock 'n' Roll Express, Buff Bagwell and Greg Gagne.
They also mention Samoa Joe, who competed as an enhancement talent against Essa Rios on WWE Jakked in March 2001.
WWE wrote: "Samoa Joe became an icon on the independent wrestling scene throughout much of the 2000s by treating his opponents' heads like they were soccer balls. A rival of both Daniel Bryan and CM Punk during their early years with the Ring of Honor promotion, the hard-hitting Samoan even battled Kenta Kobashi in the Japanese icon's most famous North American match. Joe earned his ardent fan base the hard way. But before he compelled supporters to chant "You're going to get your head kicked in!" at his shaken opponents, the near 300-pounder made a sole WWE appearance in March 2001. Competing on WWE Jakked only a few years into his career, a young Joe struggled against former WWE Light Heavyweight Champion Essa Rios in an inauspicious national debut. The burly Samoan would go on to kick the teeth out of every major independent wrestler around, but he would not be seen in WWE again."