West coast based underground filmmaker Robert Nelson, who was diagnosed with terminal cancer within the past year, passed away this week. He was 81 years old.

Nelson began making films in the early 1960s and his work stood out from his peers at the time thanks to their prankish energy and humor. His most notorious film was 1965’s Oh Dem Watermelons, a parody of racist attitudes towards blacks that divided audiences with its shocking antics. The film was originally commissioned and planned to be shown just as intermission entertainment during live shows performed by the San Francisco Mime Troupe, but its popularity turned it into a regularly programmed hit.

Other films of note include his longest work The Great Blondino (1967), a 42-minute romp that features a curious young man exploring the beguiling world around him, and The Off-Handed Jape (1967), a film in which Nelson and his filmmaking partner William T. Wiley perform facial contortions based on absurd suggestions shouted out by unseen agitators. (The off-screen voices are actually also Nelson and Wiley, who recorded the soundtrack after filming themselves.) The Off-Handed Jape is available on the Treasures IV: American Avant-Garde Film, 1947-1986 DVD box set.

According to a wonderful tribute written by close friend Mark Toscano, over the course of Nelson’s career, the filmmaker started questioning the relevance of his work, despite their wide popularity and influential nature. But, thanks to Toscano’s preservation efforts and enthusiasm, within the past few years Nelson had enjoyed and participated in retrospective screenings.