Janus (species)

The Janus were a two-faced species.

Biology
The Janus looked identical to humans, except for an identical second face on the back of their heads. For the females of the species, they 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 threatened because of her abilities. When Mayor Me needed a trap to lure the Twelfth Doctor in, she faked the death of Anah and put her in stasis. 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)