He was the husband of the filmmaker, painter, and actress Marie Menken. They achieved some renown in New York City's modern art world of the 1940s through the 1960s, both for their experimental films as well as for their salons, which brought together artists, writers, filmmakers and intellectuals. According to their associate, Andy Warhol, "Willard and Marie were the last of the great bohemians. They wrote and filmed and drank (their friends called them 'scholarly drunks') and were involved with all the modern poets."
Maas's 1956 film Narcissus stars Judith Malina (credited as Jody Malin) and Julian Beck, members of The Living Theatre, both of whom perform voice-overs for the film. He is also famous for having performed fellatio on Tom Baker for the 1963 Warhol short film Blow Job.