Mara

The Mara was an entity created from the evil in the minds of the Manussans and given independent life via the Great Crystal.

It led the Sumaran Empire. (DW: Snakedance) On the planet Deva Loka, it possessed several of the Kinda tribe. When the Doctor's companion Tegan Jovanka fell asleep on Deva Loka, the Mara possessed her through her unconscious. Using Tegan's body, the Mara sought to create chaos by pushing the Kinda to attack the Earth force on the planet. The Doctor used a circle of mirrors to make the Mara face itself and therefore make it leave Tegan and be banished once more. (DW: Kinda)

The Mara was not entirely banished from Tegan and forced her to return to Manussa. It planned to recorporalise itself using the Great Crystal, but the Doctor once more defeated it by smashing the Great Crystal. (DW: Snakedance)

Minor references

• Jack Harkness mentioned an alternate name for fairies: Mara. (TW: Small Worlds)

:Whether this indicates a connection remains unknown.

• The tenth incarnation of the Doctor mentions the Mara to his fifth incarnation when they met. (DW: Time Crash)