Try to imagine an elderly documentary filmmaker specializing in educational titles – your mental Etch-A-Sketch pad will likely dish up a stuffy Alistair Cooke type, pipe and all. Veteran filmmaker William Greaves, who won’t get more specific about his age than “somewhere in my 70s,” bears a closer resemblance to Billy Bob Thornton, with his trim physique and a wardrobe consisting of film festival gear, blue demin, and black leather.

He doesn’t know the exact number of films he’s worked on, but estimates the figure at more than 200. He’s earned more than 70 film festival awards, four Emmy nominations, and one Emmy.

His manner is so gallant it borders on deferential. He smiles nonstop. At a brunch meeting he answered questions gamely, but seemed more interested in finding out about his interviewer’s experiences. He hardly touched his fluorescently colored eggs Benedict, and waited until the end of the meal to softly declare, “I don’t think I liked this very much.”

Mr. Greaves grew up in Harlem, the middle of seven siblings. His father was a part-time minister and taxi driver and his mother was a part-time evangelist, who dabbled in poetry. The household was intellectual, and all the Greaves children were encouraged to take up creative pursuits. William studied drawing at the local YMCA and went on to attend Stuyvesant High School, where he was one of three African-Americans in a class of 35. “It was very competitive,” he said. “There was a guy named Arthur Greenspan who was getting these marvelous marks, 97s and 99s. I was always trying to keep up with him.”

His high grades helped his get into the mechanical engineering program at City College of New York. He says he was very serious about it, but at the same time he started dancing with the Pearl Primus Dance Troupe. After a year and a half, he dropped out of school to dance full-time. An actor he met on a dance production, Gordon Heath, suggested Mr. Greaves try out for a play he was involved with, and before long he was with the American Negro Theater and, eventually, the Actors Studio, working with a roster of other actors including Eva Marie Saint and Marlon Brando.

As a young black man, Mr. Greaves found it difficult to land substantial roles in the theater. He kept getting offered roles as the bumbling porter or buffoon. “It was boring and insulting. You have you realize, back then America was a fascist state.”

He and Mr. Brando bonded over the fact they were both experiencing difficulties with landing worthwhile parts. “Marlon didn’t like a lot of his roles for different reasons,” he said. “They were just vacuous uninteresting people. He wanted roles that really challenged him. He also wasn’t sure he wanted to be an actor.” The two used to take day trips together to the boxing gym in Harlem. “I remember sitting with him in a restaurant and talking about acting versus some other kind of life and he decided he wanted to go to the New School and study sociology and philosophy. He wanted a different life for himself.”

Fed up with being offered demeaning parts, Mr. Greaves decided to go back to City College to study filmmaking. “If I couldn’t do anything in front of the camera, I could do something behind it.” Also, Mr. Greaves added, he was becoming interested in African-American history at the time and “I wanted to make films about it.”

In 1952, when he was still in his mid-20s, Mr. Greaves sent himself off to Ottawa, where he worked at the then-fledgling National Film Board of Canada.

Was it at all strange to be a Harlem boy stranded in Ottawa? “No, it was delightful! People were very civilized there. White Americans frankly were in a very bad psychiatric state in terms of race relations, you know what I mean? They had all kinds of hang-ups. Ottawa was very refreshing to me. It was a smart move.”

At first he was completing assignments, but soon enough he could come up with projects he wanted to work on, and the board would provide funding. He came up with “Emergency Ward,” a cinema verite look at an emergency room, as well as 80 other titles over eight years. “It was wonderful,” he said. Another wonderful thing about Canada: He met his wife there. When he returned to New York, in the early 1960s, she came along with him and now produces his films.

Over the past four and some decades he’s put together documentaries on everyone from Mohammed Ali to peace activist/intellectual Ralph Bunche to journalist and anti-lynching activist Ida B. Wells. The diversity of his subjects makes one wonder how he chooses them. Does he feel he has a mission?

“Not a mission, per se, but there are certain areas that interest me. For example Ralph Bunche interests me because I’d like to see a very peaceful world.”

And then, inevitably, came his flirtation with Hollywood, when he went to produce Richard Pryor’s “Bustin’ Loose” in 1990.”It was fascinating in the sense it gave me a close look at the culture, the psychology of it,” he said. “Universal wanted me to stay out there and they showed me a nice house on Laguna Beach but I wasn’t ready to do that. Today it might be easier to accept. I’m more mature and I need money.”

In 1963 he made a feature-length fake cinema verite movie about a film production that Mr. Greaves says is a meditation on the Heisenberg principle of uncertainty. He added that, “It’s about a compendium of a lot of concepts picked up in mu failed pursuit of being a scientist and mystic of sorts.” It’s called “Symbiopsychotaxiplasm: Take One,” and it’s undergoing a revival, playing at several film festivals, and is likely to come to the next TriBeCa Film Festival, according to its director, Peter Scarlet. It’s a pseudo documentary about a film director working on a soap-operatic movie in Central Park. Mr. Greaves plays the director.

It screened at the Sundance Film Festival about 10 years ago. Indie filmmaker Steven Soderbergh was so impressed he put up the money for the film’s restoration. And actor Steve Buscemi met Mr. Greaves and asked if he could be involved in the sequel. Mr. Greaves obliged Mr. Buscemi, giving him a role as an onscreen consultant and using him as a cameraman as well. An unfinished version of “Symbiopsychotaxiplasm: Take Two and a Half” was submitted to the 2005 Sundance competition and is currently in post-production.

A Richard Pryor comedy, an avant-garde movie about hippies squabbling in Central Park, and PBS-type historical documentaries, one of which Variety called “solidly pro if unimaginative.” On the surface, not a lot in common there. How does he reconcile having his finger in all these pots?

“They’re not unrelated,” he said. “You’re trying to capture those, for lack of a better term, God-filled moments. That’s life, you’re trying to capture it. It’s kind of a mystical thing.”