The single largest object (excluding galaxies, the universe itself, etc.) ever identified is S5 0014+81. Brace yourself for this one.
S5 0014+81 is classified as a quasar. Upon closer examination, researchers discovered a black hole sitting at its center. Scientists anticipated finding an average-sized black hole... but were stunned when they calculated its mass at a staggering 40,000,000,000 (40 billion) solar masses.
Pause for 5 seconds to let that fully register
The Schwarzschild radius of that supermassive black hole measures 118.35 billion kilometers.
Doesn't sound too extreme, right? Well, consider this: If our sun shrank down to the size of a soccer ball, "Big Brother" would still measure roughly 37.42 km across.
Here's another visual to help put this object's scale into perspective:
