Who was the Roman guardian of entrances and exits?

The Roman guardian of entrances and exits was Janus. He was the god of doors, gates, passages, beginnings, endings, and transitions in Roman religion.

Janus was commonly shown with two faces looking in opposite directions, symbolizing his ability to watch what was coming and what was leaving. Romans associated him with doorways and gateways, both physically and metaphorically, including the transition from one year to the next. The month of January, or Ianuarius, was named after him.

Janus was honored at the beginning of important activities, and his name was traditionally invoked first in Roman prayers. His symbols included a key and a staff, emphasizing his role as a gatekeeper. The shrine of Janus Geminus in the Roman Forum was ceremonially closed during times of peace and opened during war, linking passageways with military departures and returns.

A common mix-up is treating Janus as a Greek god; he was distinctly Roman and had no direct Greek equivalent. His two-faced image also does not simply mean deceit: it primarily represents his authority over opposing directions, thresholds, and change.