Movie stars come and go, but the Muppets have endured for decades in Hollywood. Though Jim Henson passed away in 1990, his legacy has continued with new artists bringing his creations to life.

Perhaps one of the reasons the Muppets remain so beloved decades after The Muppet Show, The Muppet Movie, and the recent movie and TV reboots — even Muppet Babies are back! — is because the artists have always treated them as real people. Kermit the Frog and Miss Piggy are real actors who perform.

One of the original Muppet performers was Frank Oz, and he became a successful film director himself, directing Little Shop of Horrors, Dirty Rotten Scoundrels, In and Out, Bowfinger, and Death at a Funeral. So Oz decided to make a documentary about all the original Muppet performers and filmed conversations between himself, Fran Brill, Dave Goelz, Bill Barretta, and the late Jerry Nelson for the movie Muppet Guys Talking.

Rotten Tomatoes got even deeper with the Muppet Guys (and Brill) in an interview conducted last year at South by Southwest. Sometimes they still talk about Muppets as real actors, and other times they share the behind-the-scenes dirt.

Here are just some of the things you’ll learn about your favorite Muppets, the ones as famous as Kermit the Frog and the ones whose names you may not have known like Marvin Suggs.

And use the arrows below to rank the best Muppets ever.