For a portrait of an unconventional moviemaker, Steve Mitchell’s “King Cohen” is about as conventional a documentary as you can imagine. But the subject is fascinating enough to make up for the rather bland, but definitely affectionate, presentation.

That subject is Larry Cohen, the prolific writer, director and sometimes producer who made some of the weirdest, most memorable genre movies of the seventies and eighties—and did so with a maverick’s mad methods, often of the guerilla variety. He cooperated eagerly with Mitchell, giving extensive interviews and offering giddy observations as cameraman David C.P. Chan followed him around convention floors, and he’s an endlessly engaging fellow, well worth listening to.

But of course that’s not all there is to “King Cohen.” Mitchell has also interviewed scads of others—actors who worked with Cohen, like Yaphet Kotto, Traci Lords, Eric Bogosian, Barbara Carrera, Eric Roberts, Tara Reid, Robert Forster, Fred Williamson, and his favorite leading man Michael Moriarty; family, including both his wives; fans and scholars; and other filmmakers like Joe Dante, Martin Scorsese, J.J. Abrams, John Landis and Mick Garris. They reminiscence about his limitless imagination, his facility in scriptwriting, and his absolute single-mindedness about bringing his stories to the screen, whatever chances he had to take in the process. And their comments are almost always warm and admiring, the only exception being Williamson, who gruffly rejects some of Cohen’s recollections about their work together.

Then there is the archival material. Mitchell and editor Kai Thomasian briskly get through Cohen’s childhood, marked of course by many trips to movie palaces, and his brief career as a standup comedian, which ultimately failed to satisfy him. They slow down perceptibly for his entrance into live television in 1958 at the ripe old age of seventeen. He wrote scripts for some of the finest early anthology series on the tube, before segueing into series creation with shows like “Branded,” “Coronet Blue” and “The Invaders.” The documentary dutifully covers it all, with Cohen’s recollections adding immeasurably to the parade of stills and clips.

In 1972 Cohen turned to making features from his own scripts, though he continued contributing to television (providing story ideas, for instance, for several “Columbo” episodes), starting with the remarkable “Bone,” which he shot at his own home, and continuing with the “It’s Alive” trilogy, a couple of blaxploitation pictures and such wonderfully zany fare as “Q” (1982), “The Stuff” (1985), and perhaps most extraordinary of all, “God Told Me To” (1976). His last directorial effort, “Original Gangstas” (1996) reunited him with Fred Williamson, who had starred in “Black Caesar” (1973), but this time around was also the producer, leading to some friction between them. Afterward Cohen turned primarily to writing; even at their worst, his scripts had an outlandish pizzazz.

A couple of major themes emerge about Cohen’s moviemaking. One involves the guerilla tactics he used, shooting without permits and sometimes causing a ruckus in the process. John Landis, as well as Cohen himself, remembers the consternation he caused when, during the filming of “Q,” he had guys shooting off blanks from the top of the Chrysler Building, panicking pedestrians and bringing the NYPD down on him. He obviously enjoyed “stealing” shots and prized the edginess the method provided as well as the monetary savings.

Another motif is Cohen’s appreciation—and employment—of older artists who were often dismissed as over-the-hill. The film offers touching portraits of the friendships he developed with the great composer Bernard Herrmann in his final years, and with director Sam Fuller, whom he cast in “A Return to Salem’s Lot” (1987), and Red Buttons, who co-starred in “The Ambulance” (1990). He was less successful in bringing Bette Davis back to the screen in “Wicked Stepmother” (1989), but still treated her walking off the project in a pretty gentlemanly fashion—while contriving a way to finish the picture with her footage that rivals, if it doesn’t surpass, what Ed Wood did with Bela Lugosi’s tests for “Plan 9 from Outer Space.”

Mitchell and Thomasian proceed doggedly down to the present, unable to cover every project but offering a chronological survey broad enough to leave you astonished at the man’s inexhaustible gift for coming up with ingenious ideas and his determination to see them onscreen. Throughout Cohen proves a deliciously deadpan raconteur, even if some of the stories he tells might stretch the truth as much as his plots often strain credulity. The result is a fine tribute to a moviemaker who definitely did it his way, even if one suspects that if he were making such a documentary, it would be a lot more inventive.

Don’t confuse Larry Cohen, by the way, with Lawrence D. Cohen, who adapted Stephen King’s “Carrie” for Brian De Palma. Larry is Lawrence G.