Marx Brothers fans are familiar with the blond wig worn by Harpo. However, when the Brothers began their careers on stage Harpo actually wore a red wig. The red appeared black in black and white film and was, therefore, changed.
Here's footage of Harpo in color from a rare 1957 film (his and Chico's last screen appearance) in color with the original red wig:
And here is Harpo's voice in a few rare recordings: