Galaxy

A galaxy was a dense grouping of billions of stars and other matter which was 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. (PROSE: Alien Bodies, TV: Castrovalva, The Web Planet)

Whilst travelling with the Tenth Doctor, Donna Noble witnessed the destruction of the Mestophelix Galaxy. (COMIC: The Widow's Curse)