Galaxy

A galaxy is a dense grouping of billions of stars and other matter which is held together by powerful gravitational attraction.

Most of the Doctor's adventures took place in the galaxy known to the Time Lords as Mutter's Spiral, although he was also known to have visited other galaxies such as the Andromeda Galaxy and the Isop Galaxy.

Other known galaxies

 * Acteon Galaxy
 * Fifth Galaxy (DW: The Daleks' Master Plan)
 * Galaxy 4 (DW: Galaxy 4)
 * RE 1489 (DW: Four to Doomsday)