Name – Mara
Species – sometimes snakelike
Planet – Manussa, Deva Loka
Temperament – malevolent
Appearances – Kinda, Snakedance

The Mara is a being of pure hatred, anger and greed, and requires the fear of its victims to survive. It exists in the minds of its victims and can transmit itself telepathically, although it can also physically manifest as a giant snake. It is so evil that it cannot bear the sight of its own reflection. In the Dark Places of the Inside, it manifests as phantoms such as Dukkha, Anatta and Annica.

The Mara was created on the planet Manussa in the Scrampus system, turning the Manussan empire into the Sumaran empire. Eventually the Mara was defeated and driven out by a Manussan and cast into the "dark places beyond".

It was on the planet Deva Loka that the Doctor, Nyssa, Tegan and Adric encountered the Mara. When Tegan fell asleep near the wind chimes on Deva Loka, she became possessed by the Mara. It soon left her and possessed a native Kinda named Aris. The possessed Aris then began to stir up the normally peaceful Kinda against an expedition of human colonists who were also present on Deva Loka. The Doctor was able to prevent the humans detonating a bomb which would have destroyed their dome and killed many Kinda, and managed to trap the Mara in a circle of mirrors. As the Mara could not bear to see its own reflection, it was driven out to a place known as the Dark Places of the Inside.

Sometime later, Tegan became possessed by the Mara once again. She then navigated the TARDIS to Manussa, where a ceremony was to be held to mark the 500th anniversary of the banishment of the Mara. Using Tegan and a young Manussan named Lon, the Mara tried to obtain the "great crystal" with which it hoped to restore its corporeal existence. The Doctor was guided by an old mystic named Dojjen who showed him how to find the "still point". When the Mara tried to make its return at the ceremony, the Doctor concentrated his thought with a small replica of the great crystal, and by finding the still point was able to repel the Mara. Then by grabbing the great crystal, the Doctor broke the Mara's hold over its controlled victims, and destroyed its new snake body. This time, the Mara had apparently been completely destroyed, for good.