Janus, the two-faced Roman god of beginnings and transitions, gives the month of January its name and is linked with New Year transitions.
Roman artists commonly depicted Janus with one face looking forward and another looking backward. That imagery made him a natural symbol for the boundary between the old year and the new one. His name is preserved in Ianuarius, the Latin name from which “January” developed.
Janus was associated with doors, gates, passages, endings, and beginnings. The Roman month named for him became the opening month of the later Julian and Gregorian calendar traditions used widely today. The first day of January therefore carried a strong connection with fresh starts even beyond modern New Year's celebrations.
Janus is sometimes incorrectly described as the Roman equivalent of the Greek god Apollo or as a god of time itself. His central role was thresholds and transitions. The two faces symbolize looking in two directions, rather than a claim that he was literally a clock or calendar deity.