Promotional still of Michael Fassbender in Frank.

Director Lenny Abrahamson on Frank’s bizarre real-life inspiration

When it comes to the title character, Abrahamson didn’t use any body doubles or special effects. That’s actually Fassbender acting — and singing.

The strangest thing about Frank might not be that its main character walks around wearing an oversized fake head. The strangest thing is that it’s based on real-life figures.

The offbeat comedy is about aspiring musician Jon (Domhnall Gleeson) who thinks his big break might come with an American band led by Frank (Michael Fassbender), a lead singer whose head is buried underneath a giant papier-mache mask. Jon finds an overseas retreat to record an album less than fulfilling, but his tweets that gain a gradual following suggest otherwise.

The idea was conceived by Jon Ronson, a Welsh writer who played keyboard during the 1980s in a punk band fronted by Frank Sidebottom, a character created by the late British comedian Chris Sievey. The Sidebottom character generally sang silly tunes in a high-pitched voice, but was best known for his spheroidal, mascot-sized head that made him an eccentric cult figure of sorts.

About two decades later, Ronson was collaborating on the screenplay for the movie adaptation of his nonfiction book The Men Who Stare at Goats when he started discussing the Sidebottom character with co-writer Peter Straughan.

After that project was finished, Ronson went to work on a separate idea about outsider musicians. Although Sidebottom served as the primary basis, the list of avant-garde inspirations also includes Captain Beefheart, Daniel Johnston, and Harry Partch.

“He wasn’t a musician; he was a comic creation. Frank was a curiosity, but there was also something very moving about it,” said Irish director Lenny Abrahamson. “That became the beginning of this journey. The film is a riff on a lot of the traits of those characters.”

Although Sievey was supportive of the film before he died in 2010, Abrahamson said, some Sidebottom devotees in England haven’t been as kind with a wave of online criticism. The filmmaker argues that they might be interpreting the project too literally.

“Some fans think we’ve trampled on the purity of the original inspiration,” Abrahamson said during the recent South by Southwest Film Festival. “It’s either a biopic or it’s not. If it is, why is he American? If it’s not, why is he wearing a head? It’s a creative leap taken in the spirit of that original creation, but it’s about lots of other things as well.”

The cast includes Maggie Gyllenhaal and Autolux drummer Carla Azar as a band members, and Scoot McNairy as their manager. The music in the film is based on live recordings of the cast on location, both in Ireland and New Mexico.

When it comes to the title character, Abrahamson didn’t use any body doubles or special effects. That’s actually Fassbender acting — and singing — while wearing a giant head, something the director said offered a well-rounded portrayal without the benefit of conventional lip movements and facial expressions.

“You kind of forget about the head,” he said. “Michael’s small movements and his tiny settlings and readjustments were amazing. It’s remarkable how much you can take away and still have a three-dimensional character, but it also has this element of playful withholding. He really enjoyed that challenge.”

Abrahamson (What Richard Did) also reserved praise for the work of Gleeson, whose character adds a touch of poignancy amid the quirks as a rock-star wannabe.

“The film is a lot about the extent to which people project versions of themselves,” Abrahamson said. “Through social media, Jon is desperately projecting a version of himself that is much more exciting and ironic than the real one. In this industry, well-known actors become a brand version of themselves. The mark of greatness is not how many followers you have or how many views you get on YouTube.

“The film shows a person who’s desperate to be someone they’re not really cut out to be, and it lets them try. I think that’s pretty relevant to most of us.”