Which famous cellist guest-stars as himself in "Noël"?

Which famous cellist guest-stars as himself in “Noël”? Yo-Yo Ma does. The renowned cellist appears during the White House congressional Christmas party, where he performs Johann Sebastian Bach’s Cello Suite No. 1 in G major.

The performance is not merely decorative. Its sound becomes part of Josh Lyman’s trauma storyline: the accompanying brass quintet subconsciously reminds him of police and ambulance sirens associated with the Rosslyn shooting. Josh becomes overwhelmed by panic, linking the musical event to the episode’s central psychological conflict.

“Noël” is the tenth episode of The West Wing’s second season and first aired on December 13, 2000. Ma is credited as playing himself, rather than as a fictional character. A common mix-up is to confuse him with a famous violinist or with other celebrated cellists; the guest appearance is specifically by Yo-Yo Ma, whose Bach performance helps trigger Josh’s flashback.