Klaatu was a Canadian progressive rock band formed in 1973 and disbanded in 1982. Members John Woloschuk, Dee Long and Terry Draper lived in Toronto. They released five studio albums, the most famous of which is the 1976 debut 3:47 EST (AKA Klaatu), which, due to a rumor started by a DJ, was believed by some to be a front for new work by the Beatles.

The album's artwork contained no credits for the performers, and there were at times vocal similarities with Lennon and McCartney. That album's song "Calling Occupants of Interplanetary Craft" became a hit when covered by carpenters.

As the Beatle rumors subsided, subsequent albums garnered diminishing sales, and the fourth album, Endangered Species (1980), was produced by LA studio musicians with very little input from the band. Their last album, Magentalane (1981), was a return to the band's form (though on a smaller scale, without the elaborate orchestrations which characterized their first albums), but was never released in the US.

Klaatu was named after Michael Rennie's character in the classic science fiction film The Day the Earth Stood Still (1951). The band has reunited a number of times since their breakup for small-scale live performances.