À propos the Marx brothers, apart from the verbal dexterity, their charm was also beyond words:
Harpo is naturally most endearing to musos—notably Steven Isserlis, whose brilliant tribute is here (the link to the radio programme may be defunct, but watch this space). Note his fine historical reflections too.
Harpo’s mute persona might have been inspired by Rossini’s trio Mi manca la voce…
For Steven’s Bach, see here.