This may have been brought up but the search is searching all forums...
I was watching Community on Blu-ray, specifically Abed's Uncontrollable Christmas from season 2, and all the main cast appear but only as voice because the episode is stop-motion. You can do this with the main credits, such as Nick Bakay voicing Salem on Sabrina the Teenage Witch, but we also need a way to designate it on an episode level as well for when a cast member appears but not physically.