Janus, the ancient Roman god of beginnings, gave January its name.
Romans associated Janus with doors, gates, transitions, and passages. He was commonly represented with two faces, one looking forward and one looking backward, a fitting image for the boundary between the old year and the new.
The month of January is named after him through the Latin Ianuarius. In the Roman calendar reforms associated with Numa Pompilius and later Julius Caesar, January became connected with the start of the year, although Roman calendar practice changed over time.
Janus is often confused with Saturn because Saturnalia was a major Roman winter festival. Saturnalia was dedicated to Saturn and did not supply the name of January. The modern New Year date is a calendar convention, while Janus represents the symbolic idea of transition.