From Muppet Wiki

David Bulbeck is an actor and puppeteer who operated one of the Goblins in Labyrinth and served as an additional performer on The Muppet Christmas Carol and Muppet Treasure Island.

Bulbeck's other puppetry credits include work on the film version of Little Shop of Horrors and Who Framed Roger Rabbit. He also appeared in multiple Doctor Who episodes, between 1980 and 1983, playing such creatures as a Foamasi ("The Leisure Hive"), Castrovalvan ("Castrovalva"), and a leper-like Lazar ("Terminus").