Mara is the tempter, a devil in Buddhism, who tried to seduce the Buddha with the vision of beautiful women, also said to be Mara's daughters. Mara personifies the "death" of the spiritual life; the distraction that humans face from the spiritual path when the mundane becomes alluring or the negative seems positive. Mara can also be one’s desires that fog the mind, and has to be defeated by the person himself. In Hinduism, Mara is also the goddess of death.
Listen to an artist's rendition of the temptation of Mara:
In modern storytelling, Mara continues to be related to evil and darkness. In 2011, 2entertain is all set to release two Doctor Who Mara tales - Kinda and Snakedance.