The actor has passed away at the age of 89 after having prostate cancer.
As well as playing Rafiki in the hit Disney movie The Lion King, Robert was known for his portrayal of Benson in the sitcom Soap and the spin-off Benson.
A number of celebrities have been paying their respects on social media.
Class, Grace & Talent Personified!! RIP Robert Guillaume
— Samuel L. Jackson (@SamuelLJackson) October 25, 2017
Giant of stage + screen. Also let's remember that Robert Guillaume was among the first celebs to appear at AIDS fundraisers. Thank you, sir. pic.twitter.com/Zu1klgGAV3
— Ava DuVernay (@ava) October 24, 2017
RIP to EmmyAward winning Army vet, star of stage & screen, Robert Guillaume. 1st black actor to play the title role in Phantom of the Opera pic.twitter.com/WA2aezsfQz
— jesse Williams. (@iJesseWilliams) October 24, 2017