While some might argue for hydrogen (H₂) being the most abundant element, water is the most abundant *compound* in the universe. It's found in vast quantities throughout the cosmos, including:

* Stars: Water is a common component of stellar atmospheres.

* Planets: Water is present on many planets, moons, and even comets, often in the form of ice.

* Interstellar clouds: Vast regions of space contain water molecules in gaseous and icy forms.

So, while hydrogen is the most abundant element, water takes the crown for the most common chemical compound in the universe.