IF you don't know who Bill Hader is . . . No, scratch that; odds are, you actually do know who Bill Hader is.

For some 10 years, Hader has lurked around the fringes of the movieverse as an "oh, that guy" in Superbad, Tropic Thunder, Pineapple Express and Night at the Museum: Battle of the Smithsonian. And then there's his distinctive, invariably amusing pipes; he's the voice of the hero from Cloudy with a Chance of Meatballs and the USS Vengeance onboard computer in Star Trek Into Darkness.

Meanwhile, on TV, Hader has popped up on 30 Rock, Saturday Night Live, The Mindy Project and has worked as a producer and creative consultant on South Park.

For all these credits, 2014 has presented us with a hitherto undiscovered dimension to 36- year-old comic. Having already popped up in Spike Jonze's wry heartbreaker Her, the much-admired Hader will soon feature in The Disappearance of Eleanor Rigby trilogy.

With Wiig

This week Hader reunites with fellow SNL alumna Kristen Wiig for The Skeleton Twins, a dramedy about two grown up Gen-X siblings whose penchant for lip-synching to Starship's Nothing's Gonna Stop Us Now fails to mask their various emotional scars.

The actors must have had to sit on their jazz hands. A lot.

"Right," says Hader. "This is the first time I've ever done anything like this. I have to give a lot of the credit to director Craig Johnson and his editor, Jenny Lee. Because there was footage of us being very SNL and they were smart enough to say: 'You know what? We did laugh. And the audience might laugh. But tonally, this does not work for this movie.'"

The Skeleton Twins won the Waldo Salt Screenwriting Award at Sundance last January. But the film's darker hues are, given the players, rather unexpected. Did the tone alter how Hader normally works?

“A little bit. Because that’s how I usually know if something works or not. People laugh or they don’t,” he says.

"Here the director would say: 'That was great. Moving on.' And I'd think: Was it? But for the first three days of the shoot, I was working with [Modern Family's] Ty Burrell. Ty is a classically trained actor. He can do anything. So when he kept saying 'Hey, you're doing a really good job', that meant a lot. It kept me going."

A long time coming

Hader's rave notices for The Skeleton Twins have been a long time coming. Born in Tulsa, Oklahoma, Bill was raised by performers: between driving trucks and running an air freight company, his father enjoyed open mic nights at comedy clubs. His mother, meanwhile, was a dance instructor. The entire family, including Bill's two sisters, were movie buffs and the actor's lists – notably 200 Movies Every Comedy Writer Should See – have gained a cult online following.

During his teens, Hader wanted to be a film-maker and was friendly with Nicholas Jasenovec, who directed Michael Cera in Paper Heart, when the pair attended Scottsdale Community College in Phoenix.

Hader relocated to Los Angeles in 1999 to work as a production assistant on Spider-Man, The Scorpion King and Collateral Damage. Between jobs, the budding director, a huge Monty Python fan, honed his improv skills with Second City, the same feeder comedy troupe for SNL that launched the careers of John Candy and Catherine O'Hara, among many others.

He was eventually discovered by Megan Mullally, who introduced Hader to SNL head honcho Lorne Michaels. Since 2005, Hader has been an essential part of that show's furniture. Regular impersonations include Peter O'Toole, Vincent Price and John Malkovich.

Does he ever bring these people home? "I'm encouraged to," he says, laughing. "My wife particularly likes Dateline NBC's Keith Morrison, who has this talent for making every detail seem tragic."

And then there are recurring characters, most famously the flamboyant "city correspondent" Stefon Meyers, a very different kind of gay character to the one Hader plays in The Skeleton Twins. How did Hader, father of two girls with The To Do List writer-director Maggie Carey, become the go-to guy for camp?

"The Stefon character was just something John Mulaney and I came up with. But for us it was never important that he was gay. The joke was always that he's terrible at his job. Same with Milo in The Skeleton Twins. What I liked about the script was that he has lots of problems, but being gay isn't one of them."

The same character does, however, fit with our idea of the depressive comedian. Does that cliché have real-world merit?

“I can’t say that it doesn’t exist,” Hader says. “But I think it’s a 50/50 thing. There are people who are nice and funny and people who have a lot of problems and who are just getting through the day. They go way up and then way down. Everybody is different. Same as any profession.”

Hader has recently announced his retirement from SNL: "It was time."

So working with Justin Bieber as a guest presenter didn’t push him over the edge?

“I wouldn’t claim it was easy,” he laughs. “Let’s just say he was very non-committal.”