Final answer:
Phil Hartman was the comedian who worked as a graphic designer and created the logo for Crosby, Stills, and Nash before his comedy career.
Step-by-step explanation:
The comedian who was a graphic designer and created the logo for Crosby, Stills, and Nash before becoming famous for his characters like Troy McClure, Captain Carl, and Bill McNeal was Phil Hartman. Before his successful career in comedy, Hartman worked as a graphic designer and collaborated with various clients, including musicians. His work on the logo for Crosby, Stills, and Nash is an example of his talent as a designer.