"Little Willy" is a song written by songwriters Nicky Chinn and Mike Chapman and performed by the British glam rock band The Sweet, released in 1972 as a non-album single in the UK, peaking at #4 in the best seller charts. It was released in the US in September 1972 and also appeared on their US debut album The Sweet and became Sweet's biggest hit in the US, reaching No. 3 on the Billboard Hot 100 chart.

This is the last single on which Steve Priest, Andy Scott, and Mick Tucker did not perform, as on "Little Willy" and all previous singles, producer Phil Wainman played drums, and session musicians John Roberts and Pip Williams were on bass and guitars respectively.

"Little Willy" was used extensively in the pilot of the television series Life on Mars.

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