There was Pope John the XXIII back in the late 50s and early 60s. Hard to top that. More recently, there was Benedict XVI, but that isn’t even close.
Super Bowl LVI.
Was more interested in non-popes or monarchs, just regular people who use a Roman numeral. And while we’re on the subject, is it only a male characteristic? I am not aware of any women using a Roman numeral (other than Elizabeth II).