Which of these Roman gods was NOT based on a Greek god?
The Roman gods Jupiter, Bacchus, and Neptune are based on their Greek counterparts Zeus, Dionysius, and Poseidon, respectively, but Janus is a wholly Latin creation. Janus is the god of doorways, and many ceremonial gates throughout Rome were named “jani.” Janus also stood for beginnings, making him a fitting god for the inspiration of the name of the first month of the year, January.
Source: National Geographic