Final answer:
In "The Banker" episode of The Office, the highest-ranking employee at Dunder Mifflin is CFO David Wallace, though he does not physically appear in the episode.
Step-by-step explanation:
In S6E13 "The Banker" of The Office, the highest ranking employee at Dunder Mifflin present in this episode is David Wallace, who is the CFO (Chief Financial Officer) of the company. This specific clip show styled episode features a banker sent by Dunder Mifflin's new owners to Scranton under the guise of conducting due diligence, during which many clips from past episodes are shown as the characters recount the goings-on at the branch. Although David Wallace does not physically appear in this episode, his position as CFO places him as the highest-ranking company official.