Bob Ross donated many of the paintings he made on The Joy of Painting and didn't collect a salary from the show.
Ross often painted three of the same paintings for an episode: one pre-painted to use as a reference off camera, one that he painted during the episode, and one that he painted after the episode so a photographer could take photos for his how-to books. Ross donated many of these paintings to PBS stations to auction off for fundraising.
Ross also never took a salary from PBS for his show. Rather, he did the show for free and used the publicity to promote his line of art supplies.