Paul Allan Shaffer was born on November 28, 1949 and raised in Thunder Bay, Ontario. He studied classical piano as a child and in his teenage years joined a rock band after discovering the Beatles and Neil Young. Shaffer originally planned to earn a law degree and join his father's firm, but while majoring in psychology as an undergraduate at the University of Toronto, he found himself unable to bear giving up music. After graduation, Shaffer landed a job as musical director of a Toronto production of Godspell in 1972, where he befriended Martin Short and Gilda Radner. When Shaffer traveled to New York to record Godspell's movie album, he got a gig playing piano in the Broadway production of The Magic Show. He quickly branched out into radio work, including National Lampoon's Radio Hour, and played on other artists' recording sessions, commercial jingles, and demos.

Shaffer had previously befriended many of the comedians at the new comedy program Saturday Night Live, as well as producer Lorne Michaels, and he joined the program in 1975, writing special musical material. During his first tenure with the show, he also supported Gilda Radner on her Broadway show Gilda Live and collaborated with Dan Aykroyd and John Belushi on their Blues Brothers project, playing on their 1978 Briefcase Full of Blues album. In 1979, he briefly left SNL to star in a Norman Lear/Don Kirshner-produced sitcom, A Year at the Top, which was canceled after only six weeks. Shaffer continued his occasional acting gambits after returning to SNL, impersonating Kirshner in skits and taking a sniveling turn as record promo man Artie Fufkin in Rob Reiner's This Is Spinal Tap.

Shaffer's big break, of course, came in 1982, when he was tapped to become the musical director of Late Night with David Letterman and the leader of the World's Most Dangerous Band. The program ran on NBC through the fall of 1993, and Shaffer became an instantly recognizable celebrity. In 1991, Shaffer recorded his first album, a guest-laden affair (Dion, Ben E. King, Bobby Womack, Wilson Pickett, etc.) titled Coast to Coast, which paid tribute to the rock and soul classics Shaffer fell in love with in his younger days. In 1993, Letterman and Shaffer moved to CBS, and legal difficulties forced Shaffer to rename his band the CBS Orchestra. That year, the band recorded an album entitled The World's Most Dangerous Party, with the band billed as the Party Boys of Rock 'n' Roll. Shaffer seems poised to continue on in his current role indefinitely.