Vāyu (Sanskrit: वायु, IAST: Vāyu; Malay: Bayu, Thai: Phra Pai) is a primary Hindu deity, the Lord of the winds, the father of Bhima and the spiritual father of Lord Hanuman. He is also known as Vāta (वात), Pavana (पवन, the Purifier), and sometimes Prāṇa (प्राण, the breath).
As the word for air, (Vāyu) or wind (Pavana) is one of the Panchamahābhuta or five great elements. The Sanskrit word 'Vāta' literally means "blown", 'Vāyu' "blower", and 'Prāna' "breathing" (viz. the breath of life, cf. the *an- in 'animate'). Hence, the primary referent of the word is the "deity of Life", who is sometimes for clarity referred to as "Mukhya-Vāyu" (the chief Vāyu) or "Mukhya Prāna" (the chief of Life).
Sometimes the word "vayu," which is more generally used in the sense of the physical air or wind, is used as a synonym for "prāna". There is however a separate set of five deities of Prāna (vital breath), Mukhya-Prāna being chief among them, so that, in Hindi and other Indian languages, someone's death is stated as "his lives departed" (uske prān nikal gaye) rather than "his life departed." These five Vāyu deities, Prāna, Apāna, Vyāna, Udāna, and Samāna, control life (and the vital breath), the wind, touch/sensation, digestion, and excretion.
Vāta, an additional name for Vāyu, is the root of the Sanskrit and Hindi term for "atmosphere", vātāvaran (वातावरण).
Pavan is also a fairly common Hindu name. Pavan had played an important role in Anjana's begetting Hanuman as her child. Hence Hanuman is also called Pavan-Putra (son of Pavana) and Vāyu-Putra.
In the Mahabharata, Bheema was the son of Vāyu and played a major role in the Kurukshetra war. He utilised his huge power and skill with the mace for supporting Dharma.
In the hymns, Vayu is "described as having 'exceptional beauty' and moving noisily in his shining coach, driven by two or forty-nine or thousand white and purple horses. A white banner is his main attribute." Like the other atmospheric deities, he is a "fighter and destroyer", "powerful and heroic."
In the Upanishads there are numerous statements and illustrations of the greatness of Vāyu. The Brhadaranyaka states that the gods who control bodily functions once engaged in a contest to determine who among them is the greatest. When a deity such as that of vision would leave a man's body, that man would continue to live, albeit as a blind man and having regained the lost faculty once the errant deity returned to his post. One by one the deities all took their turns leaving the body, but the man continued to live on, though successively impaired in various ways. Finally, when Mukhya Prāna started to leave the body, all the other deities started to be inexorably pulled off their posts by force, "just as a powerful horse yanks off pegs in the ground to which he is bound." This caused the other deities to realize that they can function only when empowered by Vayu, and can be overpowered by him easily. In another episode, Vāyu is said to be the only deity not afflicted by demons of sin who were on the attack. The Chandogya states that one cannot know Brahman except by knowing Vāyu as the udgitha (the mantric syllable "om").
Followers of Dvaita philosophy hold that Mukhya-Vāyu incarnated as Madhvacharya to teach worthy souls to worship the Supreme God Vishnu and to correct the errors of the Advaita philosophy.