Harrow () is a large suburban town in Greater London, England. It serves as the principal settlement of the London Borough of Harrow, lying about 10.5 miles northwest of Charing Cross, and 5.4 miles south of Watford. The entire town, including its localities Harrow-on-the-Hill, Harrow Weald, Headstone, Kenton, Rayners Lane, South Harrow and Wealdstone, had a population of 149,246 as of the 2011 census, whereas the wider borough had a population of 250,149.
Historically in Middlesex, Harrow was a municipal borough before it became a part of Greater London in 1965. Harrow is home to a large University of Westminster campus and Harrow School. Harrow-on-the-Hill is a conservation area with listed buildings of Georgian architecture.