Who appeared on Cheers as a plumber to sweep Rebecca off her feet?

In the TV show "Cheers," the character who appeared as a plumber to sweep Rebecca Howe off her feet was played by actor John Cleese. His character, a charming and suave plumber named Duncan, creates a romantic interest for Rebecca during his guest appearance in Season 6. Cleese's comedic talent added a memorable twist to Rebecca's storyline.