Janus

Janus was a Roman god. Praefectus Thalius Maximus once prayed to him, beseeching him to "stand watch at this door and protect the humble wretches that dwell within". (PROSE: Byzantium!)

The Twelfth Doctor, Clara Oswald, and Rigsy met two female Janus, a mother and a daughter. The Doctor believed female Janus have two heads, one facing forwards that can see into the future and one facing backwards that sees into the past. In addition, female Janus are also able to concentrate their ability to look into the past and future of a specific target, making them very empathetic and able to understand others. One Janus told the Doctor that they struggle to differentiate who they are because of how much is inside them. Male Janus seem to have no special powers.

Janus burn their dead. (TV: Face the Raven)