The closest to what you are looking for would probably be Janus. He was the Roman God of beginnings and endings, of the passage of time, along with doors, gateways, and passages.

He is unique in that there really is no Greek counterpart, in many ways he is a reflection of the early Roman spiritual and broad religion and their respect for the spirits to be found all around them.

His Temple in Rome was also used to signal the beginning and ends of conflict for Rome. In times of peace it was closed, and when war was upon them it would be open and sacrifices held inside to bring victory.

Because of his nature of looking to both the past and future his traditional depiction is as having 2 faces, one looking in both directions.