Janus (species)

The Janus were a humanoid species with two faces.

Biology
The Janus looked like humans, save for an identical second face on the backs of their heads. Female Janus could see the future with their front faces and the past with their back faces. (TV: Face the Raven)

Culture
Janus traditionally cremated their dead. (TV: Face the Raven)

History
In the 21st century, two Janus took refuge in the trap street run by Mayor Me after escaping slavery. Anah disguised her daughter as her son, Anahson, so that she wouldn't be targeted for her abilities. When Mayor Me needed to set a trap for the Twelfth Doctor, she faked the murder of Anah and framed Rigsy for the crime. The Doctor was able to solve the mystery with the help of Anahson, who was able to see the past and what really happened. (TV: Face the Raven)