Tim Dirks, author and curator of the sprawling Web reference Filmsite.org, explains them this way: "Cult films are usually strange, quirky, offbeat, eccentric, oddball, or surreal, with outrageous, weird, unique and cartoony characters or plots, and garish sets. They are often considered controversial because they step outside standard narrative and technical conventions."

That covers familiar cult favorites such as Rocky Horror (1975), Freaks (1932), Kentucky Fried Movie (1977) and Sweet Sweetback's Baad Asssss Song (1971), each of which was seen as shocking, even obscene, in its day. Most were not box office hits.

A more recent phenomenon is the cult movie that finds its audience on home video. Office Space, an ironic comedy about miserable jobs from Mike Judge (Beavis and Butthead) barely registered when it opened in theaters in 1999. Once available on video, however, it found an audience that made it a perennial favorite among DVD owners.

Donnie Darko, a sad fantasy about fate released shortly after Sept. 11, 2001, disappeared quickly from theaters. But it became a breakout hit among home viewers. It was so successful that a director's cut was re-released to theaters and film festivals this year.

Ultimately, however, what makes one movie a cult favorite and another a forgotten failure is a mystery.

Larry Thomas, who once operated the defunct downtown theater The Movies, said the most reliable favorites among local cult fans were an eclectic mix of movies, "that played over and over and could play almost any time and draw a crowd."

Among them: Harold and Maude (1971), a wry romance about a suicidal young man and an elder woman; Stranger Than Paradise (1983), Jim Jarmusch's oddball black-and-white road movie; Stop Making Sense (1984), the Talking Heads concert film; Eraserhead (1977), an inexplicable, nightmarish tale from David Lynch; A Clockwork Orange (1971), Stanley Kubrick's violent social commentary; Plan 9 from Outer Space, (1959), the Ed Wood sci-fi flick voted the worst movie of all time; and Attack of the Killer Tomatoes (1978), a campy sci-fi spoof.

The most unexpected favorite, he said, was Koyaanisqatsi, a strange, non-narrative 1983 film collage by Godfrey Reggio. "It was a huge hit for us that just came out of the blue," said Thomas, "and people would come back and back and back."

Margaret A. McGurk