Māra, literally “death” or “maker of death,” is the name of the deva who tried to prevent the Buddha from achieving awakening, the name given to the class of beings he leads, and also an impersonal term for the destructive forces that keep beings imprisoned in saṃsāra:

(1) As a deva, Māra is said to be the principal deity in the Heaven of Making Use of Others’ Emanations (paranirmitavaśavartin), the highest paradise in the desire realm. He famously attempted to prevent the Buddha’s awakening under the Bodhi tree‍—see The Play in Full (Toh 95), 21.1‍—and later sought many times to thwart the Buddha’s activity. In the sūtras, he often also creates obstacles to the progress of śrāvakas and bodhisattvas. (2) The devas ruled over by Māra are collectively called mārakāyika or mārakāyikadevatā, the “deities of Māra’s family or class.” In general, these māras too do not wish any being to escape from saṃsāra, but can also change their ways and even end up developing faith in the Buddha, as exemplified by Sārthavāha; see The Play in Full (Toh 95), 21.14 and 21.43. (3) The term māra can also be understood as personifying four defects that prevent awakening, called (i) the divine māra (devaputramāra), which is the distraction of pleasures; (ii) the māra of Death (mṛtyumāra), which is having one’s life interrupted; (iii) the māra of the aggregates (skandhamāra), which is identifying with the five aggregates; and (iv) the māra of the afflictions (kleśamāra), which is being under the sway of the negative emotions of desire, hatred, and ignorance.