What Could Have Been: Carrey was originally supposed to be a cast member on Saturday Night Live when the original cast left in 1980 and Jean Doumanian was hired to create a new "Not Ready for Primetime" cast for the sixth season. Considering how terrible the 1980-1981 season was and how most of the cast has faded into obscurity (with Eddie Murphy, Gilbert Gottfried, and Gail Matthius [when she spent most of the 1990s doing voicework on kids' cartoons], as the only ones who found fame outside of their time on SNL), it was probably a good thing he wasn't picked. Carrey tried again for the 1985-1986 season (the one that saw Lorne Michaels coming back to revive his show, only for it to nearly get canceled since no one liked the new cast he brought in — which included such now famous faces as Robert Downey, Jr.., Joan Cusack, Anthony Michael Hall, and Randy Quaid, along with three cast members who would be part of the show's new Golden Age: Jon Lovitz, Nora Dunn, and Dennis Miller), and, once again, was passed over. Had Carrey been picked for the 1985-1986 season, he probably would have had more of a chance to shine (even going so far as playing then-President Ronald Reagan) and either would have joined the new Golden Age cast in 1986 or be a very entertaining one-season wonder).
Plus, the Wachowski Siblings wanted him to play Plastic Man in the never-made film based on their script. Which, even if the script was kinda crappy, still would have been epic.
He almost didn't do Ace Ventura because he didn't care for the script. He only said yes after they allowed him to work on it.