You can probably name a few right off the top of your head: Hairspray, Billy Elliot, The Producers, Sunset Boulevard. The list of stage musicals based on films goes on. Why this propensity to give films a second act on stage? And why are they almost always turned into musicals, whether they started out that way or not? Maybe we can’t get enough of a good thing. (Or, in the case of a few that shall remain nameless, we’re gluttons for punishment.)

Currently onstage in Ventura County are at least two musicals based on popular movies. Young Frankenstein is at Conejo Players Theatre in Thousand Oaks, and Heathers: The Musical is at Moorpark College Performing Arts Center. One is good fun, while the other proves how fun it can be to be bad.

Young Frankenstein, based on the 1974 classic Mel Brooks film, has music and lyrics by Brooks and a book by Brooks and Thomas Meehan. The Conejo Players production is directed by Tami Keaton with a love for the material that is apparent in every moment. The adorable Matt DeNoto imbues Dr. Frederick Frankenstein with a geeky lovability and great comic timing. With a mop of curly hair and expressive eyes, DeNoto bears a slight resemblance to the late Gene Wilder that warms the heart. The production is steeped in nostalgia to the delight of audiences that howl at famous lines and cheer for beloved characters, yet the production feels fresh, thanks to the irrepressible energy of the gifted cast.

David White is hilarious as Igor. It feels as if he has been waiting his whole life to play the role. Shayde Bridges plays Inga with kittenish sex appeal, humor and a beautiful singing voice. Elizabeth, Frederick’s fiancéE (famously played by the wonderful Madeline Kahn in the films), is portrayed by Courtney Potter with a saucy playfulness that is ribald fun. Frau Blucher (cue the horse) is played by Rita McCaffrey, complete with accent and spot-on timing. As the Monster, Noah Terry doesn’t have many lines — but he doesn’t need them, thanks to his skilled pantomime and deadpan delivery. The rest of the cast, including Andrew Nunez, Mark Fagundes, Abel Alderete and Kyle Johnson, go all-in for the ride.

On the darker side of humor is Heathers: The Musical, based on the cult 1989 teen black comedy about mean girls and jerky jocks who get their comeuppance. The fine Moorpark College production, helmed by John Loprieno, has two alternating casts, consisting of many incoming students. The young actors sing, dance and act their hearts out, and the result is a production brimming with high energy and guilty pleasure.

On this particular night, Chelsea Rifkin and Jonathan Markham played “good girl” Veronica and J.D., her bad-boy crush. The two have great chemistry that nears the boiling point. Hannah Tennenhouse, Lizzy Keiser and Hillary Michelle portrayed the Heathers with gleeful menace. Holden Streetly and Jack Powell were very funny and fittingly over-the-top as the doomed jocks. Bailey Jordon Garcia gave a beautifully touching performance as Martha, the friend Veronica leaves behind. Rounding out the cast were Evelyn Rose, Brandon Lawrence, Peter Mazzeo, Juliet Delgado and a chorus of fresh faces and strong voices. The other cast includes Danielle Williamson as Veronica; Trevor Alkazian as J.D.; Judy Tanner, Olivia Saad and Arame Fall as the Heathers; Colin Grumney and Sean Parcnejo as the jocks; and Casey Proulx as Martha. Michelle Harris steps in as Veronica Sawyer for one performance.

Heathers: The Musical, with book, music and lyrics by Laurence O’Keefe and Kevin Murphy, is packed with song and dance numbers. You have to hand it to the cast for sheer stamina. The result is a night of theater that’s a 1980s throwback treat, complete with scrunchies. You find yourself rooting for all the characters, even the ones you love to hate. The production has been wildly popular (two more shows were recently added due to increasing demand for tickets), so you don’t want to miss this “riotous, heartfelt and homicidal new show.”

With Young Frankenstein and Heathers: The Musical playing this summer, and others such as Priscilla, Queen of the Desert (Camarillo Skyway Playhouse) and Kinky Boots (Thousand Oaks Civic Arts Plaza) on the horizon, you’ll have several chances to watch your favorite movies, not just on screen but onstage as well.

Young Frankenstein plays through Aug. 13 at Conejo Players Theatre, 351 S. Moorpark Road, Thousand Oaks, 495-3715 or www.conejoplayers.org. Heathers: The Musical is onstage through Aug. 6 at the Studio Theater at Moorpark College Performing Arts Center, 7075 Campus Road, Moorpark, 378-1485 or www.moorparkcollege.edu.