The Roman god Janus gave January its name and was honored in ancient Roman New Year observances.
Janus was associated with beginnings, transitions, doorways, gates, and passages. Roman artists commonly represented him with two faces, one looking forward and one looking backward. That image made him a natural symbol for the boundary between the old year and the new one.
The month of January, Latin Ianuarius, was named for Janus. In the Roman calendar, January 1 became especially important after the calendar reforms and political changes that made it the opening of the consular year. Romans marked the day with visits, gifts, good wishes, and public religious observances.
Janus is sometimes mistakenly described as the Roman equivalent of a Greek god with exactly the same role, but he is a distinct Roman deity without a direct Greek counterpart. His two faces also do not mean he was simply a god of deception; they primarily express his connection with looking in two directions across a transition.