A container for the propellant of a rocket or spacecraft. The space shuttle has a large main external fuel tank and two strap-on solid rocket boosters, which are reusable.

The main space shuttle tank weighs 751 tonnes and supplies the three main engines with liquid oxygen and liquid hydrogen. It is divided into two sections connected by a propellant feed, with the liquid-oxygen tank on top and the liquid-hydrogen tank below. It was originally painted white but is now dark and unpainted to reduce the weight by 270 kg.

A ruptured main fuel tank caused the Challenger disaster of 28 January 1986 that killed the seven crew members.