The Roman god "Jupiter" was first known as "Zeus" to the Greeks.

The statement is true because in ancient Roman mythology, Jupiter was indeed first known as Zeus to the Greeks. The Romans heavily borrowed and adapted various aspects of Greek culture, including their mythology. Jupiter was the supreme deity in the Roman pantheon, considered the god of the sky and thunder. The Romans identified Jupiter with the Greek god Zeus, equating their characteristics and attributing similar roles and powers to them. Therefore, Jupiter essentially originated from the Greek deity Zeus in Roman mythology, making the statement true.