"The Office" was by far the most streamed TV show in 2021 according to Nielsen Holdings PLC (NYSE:NLSN). But did you realize one of the most famous and wealthiest investors in the world appeared on the show for a cameo?

In season seven, episode 24, titled the "Search Committee," the Oracle of Omaha, Warren Buffett — number nine on our list — graced the screen, appearing to be in an interview for a role at Dunder Mifflin, where he turned the flame up on his interviewers, taking a tough stance in negotiations.

Buffett, worth $109.5 billion, isn't the only billionaire to appear on...