The Alvars (Tamil: ஆழ்வார், romanized: Āḻvār, lit. 'The Immersed') are the Tamil poet-saints of South India who espoused bhakti (devotion) to the Hindu preserver deity Vishnu, through their songs of longing, ecstasy, and service. They are venerated in Vaishnavism, which regards Vishnu as the Ultimate Reality.

Orthodoxy posits the number of Alvars as ten, though there are other references that include Andal and Madhurakavi Alvar, making the number 12. Andal is the only female Alvar. Together with the 63 contemporary Shaivite Nayanars, they are among the most important saints from Tamil Nadu.

The twelve Alvars were:

The Alvars are considered the twelve supreme devotees of Vishnu in Sri Vaishnavism, who were instrumental in popularising Vaishnavism in the Tamil-speaking regions. The Alvars were influential in promoting the Bhagavata Sampradaya and the two Hindu epics, the Ramayana and the Mahabharata. The religious works of these saints in Tamil, and their hymns, are compiled as the Naalayira Divya Prabandham, containing 4000 verses, and the 108 temples revered in their hymns are classified as Divya Desams. The verses of the various Alvars were compiled by Nathamuni (824–924 CE), a 9th-century Vaishnavite theologian, who called it the "Dravida Veda or Tamil Veda". The songs of the Prabandam are regularly sung in various Vishnu temples of South India, daily, and also during festivals.

The precise meaning of the term Āḻvār (often transliterated as Alvar or Azhwar) has been debated. The common understanding is that the traditional meaning is derived from the Tamil root āḻ or azh (ஆழ்) which means "deep". From this, definitions such as "one who has plunged deep into the divine" , "who is immersed in deep meditation" , "god-intoxicated mystics" , and "one who is deeply immersed in God's experience" are commonly given.

Scholars like S. Palaniappan (2004) argue that the original term āḷvār underwent a process of sound variation, taking the form āḻvār. This linguistic shift and the subsequent folk etymology are seen to have occurred over approximately two centuries in the Srirangam area. Some linguistic analyses show that the term was initially āḷvār (from the verbal root āḷ), meaning "to rule". In this sense it could mean "those who rule, lords". This interpretation is supported by its semantic parallel with Nāyaṉār ("lord, master"), the title given to Saivite saints. Early temple inscriptions also give weight to this etymology. The term āḷvāṉ (singular masculine form of āḷvār) is also found in earlier texts, including in reference to Vishnu's devotees and even to Vishnu himself. Andal, the only woman Alvar, is referred to as āṇṭāḷ "the lady" (literally "she who rules"). This is seen as a fairly precise semantic parallel to āḷvār in the sense of "lord" or "ruler".

The legendary information surrounding the Alvars is primarily derived from a variety of Vaishnava hagiographical works, alongside insights from their own literary compositions. These sources often present traditional accounts that blend historical elements with miraculous anecdotes and theological interpretations.

There are many texts that serve as key source material for the Alvar legends. The Divyasuricarita by Garuḍavāhana Paṇḍita in the 11th century CE is considered the earliest poetical work detailing the biographies of the Alvars. The Guruparampara Prabhavam is found in multiple variations such as Guruparamparāprabhāvam-ārāyirappaḍi by Pinpaḻakiyaperumāḷ Jīyar in the 13th century CE, and Guruparamparāprabhāvam-mūvāyirappaḍi by Tṛtīya Brahmatantra Parakālasvāmi in the 14th century CE. The Vārtta Malai by an unknown author of "a fairly late date" also recounts some stories and the Ramanuja connection. The Upadeśa Ratnamālai by Manavala Mahāmuni and Periya Thirumaḍi Aḍaivu by Koil Kandāḍai Nāyan, both from the 15th century CE, also provide biographical details.