Musician Mike Schank, best known for his good guy role in the award-winning documentary film American Movie has died aged 56, according to a close friend.

Jackie Bogenberger told the Milwaukee Journal Sentinel that Schank had been treated for cancer in recent months.

He died on Wednesday.

“It spread quickly everywhere throughout his body in a matter of weeks, touching almost everything except his brain,” Ms Bogenberger said.

“He did some chemo and radiation. One of the last things Mike said to me was, ‘Hey Jackie, I feel really bad for children who have cancer. They should never have to.’”

American Movie won best documentary at the Sundance Film Festival and became a cult favourite over the years.

It gave Schank several opportunities, including a role in the 2001 film Storytelling and a voice cameo as himself on the animated sitcom Family Guy.

The 1999 documentary chronicles the making of the short horror film Coven by independent filmmaker Mark Borchart.

Schank was Borchart’s best friend, helped him film Coven, and was a prominent part of the movie, including composing its music.

Schank’s quiet humour and his honesty about his struggles with alcoholism and gambling addiction made him a fan favourite.

Among his most memorable moments in American Movie was a bloodcurdling scream he recorded for Coven.

Ms Bogenberger said throughout his battles with addiction and cancer, Schank remained “one of the most kind and selfless human beings this earth was ever blessed with”.

Friends, family members and others paid tribute on Twitter.

Lord Of The Rings star Elijah Wood called Schank a “legend”, adding: “Mike Schank forever.”

Comedian Patton Oswalt tweeted a simple “RIP.”

Rainn Wilson, best known for playing Dwight Schrute in the US version of The Office, tweeted: “This is sad. LOVED this wonderful human.”

Schank’s best friend Borchardt simply tweeted: “Stay strong forever, Mike…”

In August, Schank announced on Twitter that he was 27 years sober.

Roughly three months before Schank’s announcement, he began to tell friends and family that he had a rare form of cancer, according to Ms Bogenberger.