Kastrup is a suburb of Copenhagen, Denmark, on the east coast of Amager in Tårnby Municipality. It is the site of Copenhagen Airport. In Danish, the airport is often called Kastrup Lufthavn or Københavns Lufthavn, Kastrup.

Amager, located in the Øresund, is Denmark's most densely populated island, with more than 216,000 inhabitants. The protected natural area of Naturpark Amager makes up more than one-third of the island's total area of 96 km2.