Warren Buffett was a brief (but good) cameo, when he interviewed for a position to replace Michael Scott.
This got me googling, and stumbled across a hidden skit, which evidently Warren only played for employees at BH employee meeting. I'd like to see it. Oh well....
https://fortune.com/2011/05/19/how-warren-buffett-got-a-role-in-the-office-finale/