In its final season, Star Trek: Enterprise was a celebration of the franchise -- particularly The Original Series. That makes it shocking that it's the only Trek show in the Rick Berman era that didn't feature an appearance from any of the original cast. But that wasn't for lack of trying. The inimitable William Shatner almost made an appearance in Enterprise Season 4 that would've radically changed both the show and canon.
Source：https://www.cbr.com/william-shatner-star-trek-enterprise-season4/
