Śakra (Sanskrit) or Sakka (Pāli) is the ruler of the Trāyastriṃśa Heaven in Buddhist cosmology. His full title is Śakro devānām indraḥ (Pāli: Sakko devānaṃ indo "Śakra, lord of the devas"). In Buddhist texts Śakra is the proper name and not an epithet of this deity; conversely, indra in Sankrit and inda Pali are sometimes used as an epithet for Śakra as "lord". In the Chinese tradition, he is usually analogous with the Taoist Jade Emperor, whose birthday is celebrated on the ninth day of the first lunar month of the Chinese calendar (usually in February).
The name Śakra "powerful" is as epithet of Indra, found in several verses of the Rigveda. In Buddhist texts, Śakra's myth and character are very different from those of the Vedic Indra. According to G.P. Malalasekara, "Sakka and Indra are independent conceptions. None of the personal characteristics of Sakka resemble those of Indra. Some epithets are identical but are evidently borrowed, though they are differently explained."
The Trāyastriṃśa heaven which Śakra rules is located on the top of Mount Sumeru (cf. Meru), imagined to be the polar center of the physical world, around which the Sun and Moon revolve. Trāyastriṃśa is the highest of the heavens which is in direct contact with the Earth. Like the other deities of this heaven, Śakra is long-lived but mortal. When one Śakra dies, his place is taken by another deity who becomes the new Śakra. Buddhist stories about Śakra (past or present) are found in the Jātaka stories and in several sutras, particularly in the Saṃyutta Nikāya.
Śakra is married to Sujā, daughter of the chief of the Asuras, Vemacitrin (Pāli Vepacitti). Despite this relationship, a state of war generally exists between the Thirty-three gods and the Asuras, which Śakra manages to resolve with minimal violence and no loss of life.