As the creator of shows like “Family Guy,” “American Dad” and “Cleveland Show,” it’s no secret that Seth MacFarlane, who voices most of the characters on his shows, has tons of voices in his head.

The funnyman hosted the premiere of Saturday Night Live‘s 38th season, and used his opening monologue as an opportunity to show off his most recognizable talent — his voice!

In the beginning of the show opener, Seth pretended to speak as Family Guy’s Peter Griffin, Stewie and Quagmire before breaking out into a musical number, entitled “My Head is Full of Voices,” in which he impersonated a number of famous TV/Film characters, like Star Trek‘s George Takei and Marty McFly (played by Michael J. Fox) from “Back to the Future” and even Kermit the Frog.

Check it out below: