Who are the actors? Only Don knows, and he's not telling.
Usually seen around Daria, but not always. He's branching out, new forms of cinematography. He chooses his actors like some choose their wine. Carefully, selectively, adoringly, reverently.
This does not prevent him from putting their ass through a wringer when the time comes. He demands his actors keep working, keep pushing, and keep in-character.
Don is a Mask, but don't tell him that.
He is the reclusive artistic rival of Buck Goldberg, though it's been postulated that Don may just be one of the artsy Director's pen-names. So far, no truth has been found in these matters.