While it is difficult to definitively determine the existence of something that is truly unique and singular in the vast expanse of the universe, one example that comes close to meeting this criterion is the universe itself. As far as our current understanding of cosmology goes, there is only one universe that encompasses all of space, time, matter, and energy. This single universe, often referred to as the observable universe, is believed to have originated from the Big Bang and continues to expand over time. However, it's important to note that our knowledge of the universe is constantly evolving, and future discoveries may provide us with a more nuanced understanding of its nature.