Janus is the ancient Roman god who gave January its name and is associated with looking toward the past and future.
Janus was linked with doors, gates, beginnings, transitions, and endings. Roman artists commonly represented him with two faces, one looking forward and one backward. This imagery made him especially suitable for the symbolism of New Year, when people reflect on the year that ended while anticipating the one ahead.
The Roman month Ianuarius, or January, was named for Janus. The month eventually became the first month of the Julian calendar and of the Gregorian calendar used in much of the modern world. January 1 was not always the universal start of the year in every historical society, but its association with new beginnings is now widespread.
Janus is not the same as Saturn, the Roman god of agriculture and time-related imagery. Nor is he simply a Roman version of a generic New Year figure; he is a distinct deity with his own religious functions.