He penned hit songs for the Monkees (“Cuddly Toy”) and Three Dog Night (“One”) and was one of the earliest rock artists to give serious attention to the elegant Great American Songbook repertoire of pre-rock pop songs. At the same time, Nilsson was notorious as one of the hardest-partying rock stars of the '70s, a lifestyle that led to the heart attack that felled him at age 52 in 1994.

As comedian Tommy Smothers points out during the two-hour film, Nilsson’s name today elicits one of two reactions: tremendous admiration or a blank stare. He became part of the Beatles inner circle near the end of the band’s life, and continued close friendships with them after the breakup. He won two Grammy Awards: one for his 1969 recording of “Everybody’s Talkin’,” the Fred Neil song that was also used as the theme for “Midnight Cowboy,” the other in 1972 for his performance of the ballad “Without You.”

They’re referring to Harry Nilsson , the Brooklyn-born, L.A.-transplant singer and songwriter whose extraordinary musical gifts were overshadowed only by his predilection for self-destruction, and whose heartbreaking life story is the focal point of “Who Is Harry Nilsson (And Why is Everybody Talkin’ About Him)?” a deeply felt documentary opening a one-week Los Angeles theatrical run Friday at the Laemmle Sunset 5 in West Hollywood.

Songwriter Jimmy Webb calls him “the best singer of our generation.” Filmmaker and Monty Python alumnus Terry Gilliam describes him as “a fallen angel.” Randy Newman compares his knack for writing indelible melodies to Franz Schubert, Paul McCartney and Elton John. Superstar producer Richard Perry, among others, considers him the American counterpart to the Beatles.

Writer-director John Scheinfeld covers the many ups and downs of his life thoroughly and empathetically, without sentimentalizing or rationalizing away the demons that Nilsson struggled with, and eventually succumbed to.

“I had first come across Harry’s music when I was in college, but I wouldn’t say I was an obsessive fan,” Scheinfeld said Thursday. “The attorney for the Nilsson estate had seen some of my [documentary] work and asked if I’d be interested in doing something on Harry. I always knew the music, but I didn’t know that much about his story. The more I researched it, the more I discovered what an extraordinarily gifted artist he was and what an extraordinarily complex human being he was, which makes for some great drama.”

That drama begins with his impoverished childhood in New York, his father’s abandonment of him and his mother when he was 3 -- which he sang about movingly in the song “1941” -- his move to California at 15 because his extended family could no longer afford one more mouth to feed, his dabbling with pop music in an Everly Brothers type act while still in his teens, and then his remarkable success.

While working as a bank accountant in the San Fernando Valley, he landed a deal as a songwriter for a small publisher, earning $50 a week. When the Monkees discovered the bouncy charms of his songs and decided to record “Cuddly Toy” for their 1967 album “Headquarters,” his publisher told him quietly on the way out of the TV studio, “You can quit your job at the bank now.”

Nilsson made his debut as a recording artist that same year with “Pandemonium Shadow Show,” a winsome album that ran counter to the often bombastic excess of the psychedelic rock that was so much the rage at the time. When Beatles publicist Derek Taylor heard it, he sent copies to the Fab Four, and it’s delightful to hear audio of Nilsson himself retelling the story of receiving successive transatlantic phone calls out of the blue from John Lennon and Paul McCartney singing his praises.

Producer Rick Jarrard, who shepherded Nilssons' earliest albums for RCA, speaks sadly about how he changed after accepting an invitation to hang out with the Beatles at Abbey Road studio. “I believed Harry could be a monster artist,” Jarrard says in the film, “and frankly I was probably the only one who believed that because he was so different….When he came back from England, he was a person I no longer knew.”

Nilsson’s public profile rose considerably when “Everybody’s Talkin’” hit the charts and movie screens in 1969, and after teaming with producer Perry for 1971’s “Nilsson Schmilsson” album, which included “Without You,” he was a full-blown rock star. That same year he created an animated TV special, with Ringo Starr narrating, called “The Point” that was a ratings hit when it aired on ABC.

Yet, pal Eric Idle says, “He didn’t think he deserved the acclaim, and he used alcohol to hide.”

That contributed heavily to the long downward spiral Nilsson’s life and career took after his mainstream breakthrough. “Son of Schmilsson,” the follow-up to “Nilsson Schmilsson,” was considerably more scattered. He then parted ways with Perry to pursue a pet project, hiring Frank Sinatra arranger and conductor Gordon Jenkins to work on a collection of pop standards that predated similar efforts by Linda Ronstadt, Carly Simon and eventually Rod Stewart and rafts of other rock-era singers.

Nilsson infamously helped fuel John Lennon’s long “lost weekend” in Los Angeles while he had separated from Yoko Ono during a time of marital strife. During that time, Lennon produced Nilsson’s 1974 album “Pussycats,” which participants recall as an ever-escalating contest between two musical greats bent on out-destructing each other.

After Lennon was shot to death in 1980, Nilsson turned the bulk of his time and energy to promoting handgun control legislation. Then he discovered that much of the money he’d earned as a recording artist had been embezzled and he was teetering on the edge of bankruptcy. A third marriage late in life, to Una O’Keeffe, and the births of six more children -- he previously had a son, Zach, with his second wife, Diane -- appears to have set him back on a healthier life path, during which he helped turn his finances around for the benefit of his family.

By then, however, the damage had been done. He had diabetes and survived one heart attack in early 1993, but not a second one about 11 months later.

Even two hours isn’t enough to cover everything -- there’s no mention of the charming theme song he composed and sang for “The Courtship of Eddie’s Father” TV series that spread his music to millions of viewers who might not otherwise have known him, and it bypasses, understandably, his music for Otto Preminger’s long-forgotten 1968 film “Skidoo.”

After a long period during which Scheinfeld had to navigate clearances for the 61 Nilsson songs touched on in this documentary, it’s finally getting limited distribution. What was planned as a one-week stint in New York last week was extended for a second week, and after this week’s run in West Hollywood, Scheinfeld is taking the film for successive one-week engagements in Portland, Ore., and San Francisco.

There’s probably a one-hour edit that could heighten the film’s chances for a shot at a PBS airing at some point, without seriously detracting from the storytelling. The theatrical version is slated to be released next year on DVD, with 93 minutes of bonus material for those who are Nilsson obsessives.

“Whenever I reached out to people and said ‘I want to interview you about Harry,’ ” Scheinfeld said, “You could tell they were smiling.…What really struck me about making this was how much all these people really loved him. For what he was, and in spite of what he was, they loved him.”

-- Randy Lewis

Photo: Harry Nilsson in 1991. Credit: Ellen Jaskol / Los Angeles Times