The largest known black hole in the universe is 18 billion times more massive than our sun, it was announced at this week's meeting of the American Astronomical Society. The object, referred to as 0J287, is orbited by a smaller black hole, which aided astronomers in making the measurement. More at Space.com(1).
Image credit: NASA/JPL-Caltech

1. http://www.space.com/scienceastronomy/080109-aas-massive-black-holes.html