Janus (Greek: Ianus)

Janus had two faces looking in opposite directions: one to the past, one to the future. He presided over all beginnings, transitions, and endings. His temple doors in Rome were open during war and closed during peace — they were almost never closed. He was invoked at the start of every prayer and ceremony. The month Ianuarius (January) was named after him — the door between the old year and the new. Though more Roman than Greek, the concept of a liminal deity guarding thresholds has deep Greek roots in figures like Hermes and Hecate.