The early scenes of the documentary look like some lost reel from "This Is Spinal Tap," spanning what seems like half of rock history -- complete with hem lengths and haircuts.

But the protagonist is not a metalhead but a Zelig-like figure: Here he is as a squeaky-clean pop idol in the Frankie Avalon mode, gazing bashfully. He shows up on L.A.'s Sunset Strip at its wildest. Next he's part of a mop-topped boy band in swinging London. Then he's an artsy songwriter brooding behind scarves and cool shades. Finally, he's a baritone singer who combines depression with extravagant theatricality -- a sort of Leonard Cohen gone Vegas.

Just who is this guy? For the uninitiated, he's Scott Walker -- born Noel Scott Engel in small-town Ohio. And now, at 66, he continues to be the reclusive hero to Brit rockers, hipster intellectuals, Mojo magazine readers and swooning sexagenarian German women. But he remains a mystery to nearly all.

Even David Bowie, a longtime fan, feigns bafflement during his on-screen appearance in "Scott Walker: 30 Century Man," a documentary opening Friday at the Nuart Theatre in West Los Angeles. "Why, I don't know anything," he offers with a sly smile. "Who knows anything about Scott Walker?"

Many acolytes

Bowie, the film's executive producer, is not the only well-known musician deeply influenced by this icon of obscurity. (Bowie's so-called Berlin Trilogy of albums from the late '70s clearly bears Walker's stamp.) Johnny Marr of the Smiths, Sting, polymath Brian Eno, Damon Albarn of Blur and Gorillaz, trip-hop singer Dot Allison and Radiohead's Jonny and Colin Greenwood all show up on camera; Bono and X's John Doe also are reportedly fans. (Melancholy rocker Nick Cave, who doesn't appear in the film, also seems to be especially influenced by Walker's work.)

Experimental musician and performance artist Laurie Anderson, who works in the place where rock, classical and experimental music come together, calls herself "inspired by his sense of danger."

She still remembers the first time she heard Walker's music. "My immediate reaction was complete attention -- which pretty much describes listening to him since then." His signature, she said, is "a roaring big voice with ragged edges full of sharp things."

Most of Walker's influence came in after he left British sensations the Walker Brothers -- a trio who were not actually British, not really brothers and not named Walker -- and launched a solo career.

The film tries to make the point that he was "at once out of step with current trends and light years ahead of them," as the film's notes have it.

"Their success as a band was up there on a Beatles level for a couple of years, and then it drifted away," said Chris Walter, a photographer who shot the trio and then the solo artist in his native England in the '60s and '70s. "Scott was always the private one; you never 'hung out' with Scott. He was this enigmatic figure."

Walker's solo years are about as far from the hugely, if temporarily, popular trio as could be: Walker was inspired at that point not by the bright melodies of '60s pop or the swirl of psychedelia but rather by Samuel Beckett, Belgian crooner Jacques Brel and the films of Ingmar Bergman.

His song about Bergman's "The Seventh Seal," from the 1969 record "Scott 4," failed to chart anywhere in the known universe. But that poor-selling solo album -- Walker's first commercial flop -- became a major touchstone for many contemporary musicians.