Janus is the Roman god of the new year, with two faces looking toward the past and the future. In his right hand he holds a key and in his left a staff. He is a god of peace whose worship was more central in matrifocal times. The month of January is named for him. Janus is a winter god, the counterpart of the summer goddess Juno. From the Pagan Book of Days:

Janus is the male equivalent of one of the versions of the goddess Juno-Janus, who in her two-faced aspects of Antevorta and Postvorta looks simultaneously forward and backward as does Janus. January marks the beginning of the new year yet contains elements of that which went before. Its quality is thus one of new possibilities but constrained by that which took place in the old year before it.

Sources

Jordan, Michael. Encyclopedia of Gods: Over 2,500 Deities of the World. New York: Facts on File, 1993.

Pennick, Nigel. The Pagan Book of Days: A Guide to the Festivals, Traditions, and Sacred Days of the Year. Rochester, VT: Destiny Books, 1992.