Karen Leigh Prell is a puppeteer and animator. Born in Florida, she first worked with Jim Henson in 1979 in small roles on Sesame Street. She subsequently worked on the final season of The Muppet Show, assisting and playing various bit parts (such as the title character in "Rockin' Robin.") She also performed Deena and others on Sesame Street in the early '80s, but made her greatest contribution performing Red Fraggle on Fraggle Rock.
Prell also performed on the Creature Shop films Dreamchild and Labyrinth. During the latter film, she first became romantically involved with future husband Mike Quinn, as they made each other's goblins flirt during lulls in shooting.
In 1997, Prell transitioned into computer animation, working on several Pixar projects, including the shorts Geri's Game and For the Birds and features A Bug's Life and Toy Story 2. Recent animation credits have included some of the CGI animation in Disney's Enchanted, work for Tippett Studio on The League of Extraordinary Gentlemen, Son of the Mask, animating the award-winning video game Portal 2, and Frank Oz's The Stepford Wives.
Demonstrating that her affection for the Muppets has not waned, however, Prell attended MuppetFest in 2001, resplendent in a homemade Red Fraggle cap, and also participated in the Fraggle Rock: Complete First Season bonus features. In 2005, she reprised her role of Red Fraggle, in voice over, as host of "Fraggle Challenge," a bonus feature on the Doin' Things That Doozers Do and Down in Fraggle Rock DVD's.
She currently works as an animator with video game company Valve Corporation, where she was able to apply her experience with puppets to bring realistic movements to the robot characters of the award-winning game Portal 2.
- The Muppet Show: The Robin, other season 5 characters
- Sesame Street: Deena
- Fraggle Rock: Red Fraggle, Wingnut Doozer, Fluffinella, Baby Tree Creature, Beastie, Gorg's Killer Souffle, Judge Gavel Doozer, Marly Fraggle, Modem Doozer, Balsam the Minstrel (occasionally)
- Rocky Mountain Holiday: Various singing roles
- The Fantastic Miss Piggy Show
- The Muppets Take Manhattan: Yolanda the Rat
- Dreamchild: The Dormouse (puppeteer)
- Labyrinth: Firey 2 (lead puppeteer), The Junk Lady (puppeteer), The Worm (puppeteer), Helping Hands, Goblins (puppetry only)
- The Tale of the Bunny Picnic: Babble, Baby Bunny, Great-great-great-great Grandmother
- A Muppet Family Christmas: Maureen the Mink, Red Fraggle
- The Ghost of Faffner Hall: Mimi
- Mother Goose Stories: Gosling #1, Dicky Bird Peter, Topiary Peacock, Little Boy Blue's Mother, Cow, Old Mother Hubbard, Cat, various
- The Muppet Christmas Carol: The Ghost of Christmas Past (puppetry only), Daughter Mouse
- The Animal Show: Ollie the Tapir (first season only), Tizzy (first season only), Alexis the Giraffe, Bernice the Warthog, Hetty the Hedgehog, Kasey the Kangaroo, Leah the Fruit Bat, Lydia the Ostrich, Arlene the Aardvark, Hillary the Owl, Charlotte the Penguin, Rhonda the Raccoon, Hetty the Hedgehog, Blanche the Manatee, various animal voice-overs
- Muppet Treasure Island: Pirates and background characters (uncredited) 
- Sesame Street 4-D Movie Magic
- Late Night Buffet with Augie and Del: Spank
- The Muppets: Chickens, Penguins, background roles (all in "Life's a Happy Song" finale)
- "Do It Anyway" music video: Red
- Fraggle Rock-a-Thon promos: Red Fraggle
- Prell originally auditioned for Mokey Fraggle on Fraggle Rock.
- She is credited as an illustrator on some Muppet coloring books.
- Official site
- Muppet Central's interview with Karen
- 12/15/1979 - Karen Prell comes in from Washington State