Below is a list of the largest galaxies so far discovered by size.
The order of this list is speculative, for the following reasons:
Galaxies don't have precise boundaries. From the center of mass, the stars just drop down in density proportionally with greater distance. This list puts the boundaries of galaxies within the 1 star per hundred light year squared critical limit, where stars will hold each other through gravity.
Most galaxies have uncertain emissions of light at different wavelengths. Such an example is IC 1101 whose X-ray emission extends to 5.5–6 million light years despite its smaller stellar diameter.
Most galaxies undergo gravitational perturbations, making their stars spread out, such as the Comet Galaxy. This list only puts the boundaries where the gravity of the galaxy is dominant and not by tidal tails or other interactions.
