Jimmy Heath, Willie Nelson, and Wynton Marsalis improvise together at the Twelth Annual Kennedy Center Mark Twain Prize, airing on PBS stations nationwide on Wednesday, November 4 at 8 p.m. ET.

Dick Gregory thanks Bill Cosby for his effects on other 'negro' comedians at the Twelth Annual Kennedy Center Mark Twain Prize, airing on PBS stations nationwide on Wednesday, November 4 at 8 p.m. ET.

Watch as Phylicia Rashad thanks Bill Cosby for the best acting advice of her career at the Twelth Annual Kennedy Center Mark Twain Prize, airing on PBS stations nationwide on Wednesday, November 4 at 8 p.m. ET.

Watch as Rita Moreno serenades Bill Cosby, winner of the Twelth Annual Kennedy Center Mark Twain Prize, which airs on PBS stations nationwide on Wednesday, November 4 at 8 p.m. ET.

Watch as Malcolm Jamal Warner talks about almost not being cast on "The Cosby Show" at the Twelth Annual Kennedy Center Mark Twain Prize, airing on PBS stations nationwide on Wednesday, November 4 at 8 p.m. ET.