Rogue planet

A rogue planet was a planet which wandered through space instead of orbiting a star.

Mondas became a rogue planet when it left the vicinity of the star Sol. Following an indeterminate amount of time it returned to the area of space it had left, where it was destroyed. (TV: The Tenth Planet, AUDIO: Spare Parts)

Skardal was a rogue planet which threatened to collide with both Skaro and Mechanus. It was later destroyed by the Daleks. (COMIC: The Rogue Planet, Impasse)

Voga became a rogue planet when most of it was destroyed by the Cybermen. It eventually settled into an orbit around Jupiter. (TV: Revenge of the Cybermen)

Vortis became a rogue planet when the Zarbi Supremo set it on a course to the solar system. Control of the planet was later returned to the Menoptera. (PROSE: The Lair of Zarbi Supremo)

Earth and 26 other planets became rogue planets in the Medusa Cascade when they were captured by the Daleks. They were later returned to their original positions by the DoctorDonna in 2009. (TV: The Stolen Earth / Journey's End)

Malcassairo was a rogue planet that existed near the end of the universe. It was home to the Malmooth, the Futurekind, and, briefly, humanity. It was later destroyed by heat death at some point after the Doctor, Martha Jones and Jack Harkness escaped to the 21st century. (TV: Utopia)