David Duchovny and Gillian Anderson weren't the only celebrities on The X-Files, but many guest actors just weren't celebrities yet. The X-Files let fans join Mulder and Scully in the chase for conspiracies, ghosts, and aliens for much of the '90s. Many of the characters they ran into were played by people who would later become famous. The show's helped pave the way for many future stars, as X-Files cameos from future stars were plentiful.
With 10 seasons, including 2016 reboot, X-Files episodes provided plenty of chances for stars to show up as guests. In fact, you'll find household names such as Ryan Reynolds, Jack Black, Brian Cranston, Aaron Paul, and Jane Lynch all appeared on the show. Some of the stars who appeared on the show even owe their careers to their appearance.
The truth is out there, but the 33 stars who made appearances on The X-Files before they hit it big, they're below.