Please remember that actor/actress stories are not permitted, as stated in the TOS.

As The Office is a mockumentary, there is some grey area with real life people popping up in stories.

An example of what would be ok: real life talk show hosts/comedians appearing to interview the reality tv stars at Dunder Mifflin.

An example of what would not be ok: Any of the current cast appearing in a story as themselves. There is some confusion with Creed as he is somewhat playing himself, but so long as you are writing based off fact from the show, and not fact from his real life, I don't think that would cross any boundries.