Simplify the following text for a Grade 12 native English-speaking person.
Original: He also made guest appearances in such Canadian-filmed television serials as Smallville , Supernatural , Flash Gordon , Stargate Atlantis and Stargate SG-1 .
Simplified: He also guest starred in such Canadian-filmed television shows as Smallville , Supernatural , Flash Gordon , Stargate Atlantis and Stargate SG-1 .