雅努斯（拉丁语：Ianus），是罗马神话中的门神、双面神，被描绘为具有前后两个面孔或四方四个面孔，象征开始。罗马士兵出征时，都要从象征雅努斯的拱门下穿过，发展成四方双拱门，后来欧洲各国的凯旋门形式都是由此而来。雅努斯是罗马本土最原始的神，拉丁语“1月”Januarius这个词也是起源于他，演变成西方各国的语言。

In ancient Roman religion and myth, Janus (/ˈdʒeɪnəs/; Latin:Ianus, pronounced [ˈjaː.nus]) is the god of beginnings, gates, transitions, time, doorways, passages, and endings. He is usually depicted as having two faces, since he looks to the future and to the past. It is conventionally thought that the month of January is named for Janus (Ianuarius), but according to ancient Roman farmers' almanacs Juno was the tutelary deity of the month.