The largest known object in the universe is a structure called the Hercules-Corona Borealis Great Wall. It is a massive cosmic filament or supercluster of galaxies located about 10 billion light-years away from Earth. The Great Wall is estimated to be about 10 billion light-years long and contains thousands of galaxies. It was discovered in 2013 and has since been considered one of the largest-known structures in the observable universe. It's important to note that our understanding of the universe is constantly evolving, and new discoveries may emerge in the future that could challenge our current knowledge.