A Satellite Galaxy is a small Galaxy, often a Dwarf Galaxy, orbiting a larger galaxy. A number of galaxies in the Local Group are satellites of the Milky Way or Andromeda. Some of the 30 known satellites of the Milky Way:
Among Andromeda's satellites:
Satellites in the Local Group are still being discovered and Dwarf Galaxies are even harder to identify in more distant groups and clusters.
Large Magellanic Cloud (LMC)
Sagittarius Dwarf Elliptical Galaxy (Sgr dE)