As far as spiral galaxies go, the Milky Way is a relative pipsqueak, especially when compared to one known as NGC 6872, a barred spiral galaxy located some 212 million light-years from Earth in the constellation Pavo.
Spanning 522,000 light-years from end to end — roughly five times larger than the Milky Way — NGC 6872 has been crowned the king of spiral galaxies, based on an analysis of data gathered by NASA’s Galaxy Evolution Explorer telescope.
The galaxy has a diameter of approximately 6 million light years, which makes it currently (as of 2012) the largest known galaxy in terms of breadth. It is the central galaxy of a massive cluster containing a mass (mostly dark matter) of roughly 100 trillion stars. Being more than 50 times the size of the Milky Way and 2000 times as massive, if it were in place of our galaxy, it would swallow up the Large Magellanic Cloud, Small Magellanic Cloud, Andromeda Galaxy, and Triangulum Galaxy