The biggest single object (not counting galaxies, universe, etc.) ever discovered is S5 0014+81. Prepare to have your mind blown.
S5 0014+81 is a quasar. Upon further inspection they found out that a black hole resides at the center of the quasar. Scientists were expecting an average sized black hole… but were surprised to find out that the mass of the black hole was a massive 40,000,000,000 (40 Billion) Solar Masses.
*Waits 5 seconds to let that sink in*
The Schwarzschild radius of that superheavy black hole is 118.35 Billion Kilometers.
Doesn’t sound like much, eh? Well, here is the thing: If our sun were the size of a soccer ball, “big bro’s” diameter is 37.42km.
Here is another picture to help you deal with the size of this object:
