In Greek mythology, what was Zeus’s Roman equivalent called?

Zeus’s Roman equivalent was called Jupiter.

Greek Zeus and Roman Jupiter were both supreme sky gods who ruled the other major deities. Jupiter’s name comes from the Latin Iūpiter, connected with an older Indo-European title meaning “father god.” His traditional Roman title, Optimus Maximus, means “Best and Greatest.”

Jupiter was associated with thunder, lightning, oaths, law, and political authority. His principal Roman temple stood on the Capitoline Hill in Rome, where he was worshipped with Juno and Minerva as the Capitoline Triad.

Jupiter is not the same figure as Neptune, the Roman counterpart of Poseidon, or Mars, the counterpart of Ares. Roman writers often adapted Greek myths to Jupiter, but Roman religion also gave him distinct civic ceremonies and political importance.