Janus was the ancient Roman god associated with doorways and transitions, and his name gives January its English name.
Janus was commonly represented with two faces looking in opposite directions. This imagery suited his connection with beginnings and endings, entrances and exits, and looking backward and forward at once—ideas that fit the transition into a new year.
The Roman month Ianuarius, named for Janus, became January in English. In the later Roman calendar, January 1 served as the beginning of the consular year, helping establish the date’s importance as a civic new-year marker.
Janus is not the same figure as Saturn, the god honored during Saturnalia, a separate Roman festival held in December. Modern New Year customs are not direct copies of one single Roman ceremony, but the month’s name preserves a clear link to Roman ideas about beginnings and thresholds.