Giacomo Caneva, photograph of a statue of Jupiter in the Campana collection, 1850s.
Key myth
A god with no Greek counterpart: invoked first in any prayer. His temple's doors stood open in war and were closed in peace; Augustus boasted of closing them three times. January is named for him.
Where sources differ or caution applies. A Roman original; Ovid's Fasti is the fullest source.
Deities in other traditions who share a theme with Janus: trickery, boundaries and travel, creation and first beings. This is overlap in one area only.