The two galaxies with the most mass are the Milky Way and the Andromeda galaxy, which is about 3 million light years away. This means it takes light 3 million years to reach Andromeda from the Milky Way.
Many of the other galaxies in the group are satellite galaxies of the Milky Way or Andromeda. Among the satellites of the Milky Way are the Greater and Lesser Magellanic clouds. Andromeda's satellites include M32, NGC 147 and Andromedas I through XXIX.Learn more about Stellar Astronomy