Adi Shankara  (788 CE - 820 CE , also known as Śaṅkara Bhagavatpādācārya and Ādi Śaṅkarācārya was an Indian philosopher from Kalady of present day Kerala who consolidated the doctrine of advaita vedānta. His teachings are based on the unity of the ātman and brahman— non-dual brahman, in which brahman is viewed asnirguna brahman, brahman without attributes.

Shankara travelled across India and other parts of South Asia to propagate his philosophy through discourses and debates with other thinkers. He is reputed to have founded four mathas ("monasteries"), which helped in the historical development, revival and spread of Advaita Vedanta. Adi Shankara is believed to be the organizer of the Dashanamimonastic order and the founder of the Shanmata tradition of worship.

His works in Sanskrit concern themselves with establishing the doctrine of advaita (nondualism). He also established the importance of monastic life as sanctioned in the Upanishads and Brahma Sutra, in a time when the Mimamsaschool established strict ritualism and ridiculed monasticism. Shankara represented his works as elaborating on ideas found in the Upanishads, and he wrote copious commentaries on the Vedic canon (Brahma Sutra, principalupanishads and Bhagavad Gita) in support of his thesis. The main opponent in his work is the Mimamsa school of thought, though he also offers arguments against the views of some other schools like Samkhya and certain schools of Buddhism.

Although Lord Śiva, in the form of a brāhmaṇa (Śaṅkarācārya), preached the false philosophy of Māyāvāda, Śrī Caitanya Mahāprabhu nevertheless said that since he did it on the order of the Supreme Personality of Godhead, there was no fault on his part (tāṅra doṣa nāhi).
Sri Caitanya-caritamrta,  Adi-lila