Was Grand Lord Crisis Really The Great Leader?

In the Showa era, there was the mysterious villain known as the Great Leader. Either this guy frequently changed forms, used extensions of himself or just used decoys at the end of most Kamen Rider series. As I'm trying to watch more of the Showa era (and I prefer the Heisei era) there's always this "Great Leader" guy I keep hearing about. Just remember, this is a fan theory and nothing more. Toei hasn't released any official word about this one. Also note that just because the late Naya Goro voiced him doesn't automatically make him the Great Leader. With my rather limited knowledge of Kamen Rider's Showa era from Kamen Rider Black RX, there's some hints that Grand Lord Crisis is the Great Leader. Maybe, he's not Gorgom's founder since Kamen Rider Black was supposedly separate from the rest of Showa but Black RX created a retroactive continuity for that. The 10 other Kamen Riders of the Showa era were seen training for the final battle with...