Chaitanya Mahaprabhu (Bengali: মহাপ্রভু শ্রীচৈতন্য দেব; Sanskrit: चैतन्य महाप्रभु, romanized: Caitanya Mahāprabhu), born Vishvambhara Mishra (IAST: Viśvambhara Miśra) (18 February 1486 – 14 June 1534), was an Indian Hindu saint from Bengal and the founder of Gaudiya Vaishnavism. Chaitanya Mahaprabhu's mode of worshipping Krishna with bhajan-kirtan and dance had a profound effect on Vaishnavism in Bengal.

He is considered the chief proponent of the Vedantic philosophy of Achintya Bheda Abheda. The concept of inconceivable difference in non-difference, known as achintya-bhedabheda, was explained later by Jiva Gosvami in his book Bhagavat Sandharbha, and in his Sarva-samvadini.

Mahaprabhu founded Gaudiya Vaishnavism. He expounded Bhakti yoga and popularised the chanting of the Hare Krishna Maha-mantra. He composed the Shikshashtakam (eight devotional prayers).

Chaitanya is sometimes called Gauranga (IAST: Gaurāṅga) or Gaura due to his molten gold–like complexion. His birthday is celebrated as Gaura-purnima. He is also called Nimai because he was born underneath a Neem tree.

The religious hagiographies of Gauḍīya sampradāya are the only sources available for the reconstruction of Caitanya's life. These texts (in Sanskrit and Bengali), consider Caitanya to be an avatāra of Kr̥ṣṇa, Svayaṁ Bhagavān, Rādhā-Kr̥ṣṇa (joint and separate), Nārāyaṇa, Viṣṇu, and Jagannātha. A canonical narrative was accepted by the Gauḍīya community in the early 1600s via the Caitanya Caritāmr̥ta of Kr̥ṣṇadāsa Kavirāja, which has been described as the "final word" on Gauḍīya history and theology.

Chaitanya was born in a Brahmin family as Viśvambhara Miśra aka Nimāi, the second son of Jagannātha Miśra and his wife Śacī Devī, the daughter of Nilambara Chakrabarti, both Brahmins of Sylhet region. Jagannātha Miśra's family were from the village of Dhakadakshin in Srihatta (Sylhet) (now in Bangladesh). The ruins of their ancestral home still survive in present-day Bangladesh. The hagiographies of Caitanya portray his birth as a divine event and state that it predicted his future mission of propagating harināma saṃkīrtana in Kali Yuga.

The accounts of Caitanya's childhood are depicted to be reminiscent of Kr̥ṣṇa's childhood playtimes. While still a student, his father died, and he soon married Lakṣmīpriyā. He travelled to east Bengal to become a scholar and support his family, but his wife died in his absence. He then married Viṣnupriyā, the daughter of paṇḍit Sanātana Miśra. Viśhvambara, also known as Nimāi Paṇḍit, was a promising Sanskrit scholar and is said to have once defeated Keśava Bhaṭṭa of the Nimbārka school in a debate on Sanskrit prosody in an example of "superhuman erudition".

In 1508-1509 he left Nabadvip to go to Gaya to perform śrāddha, a ritual homage to his dead father. There, he met an ascetic named Īśvara Purī, who initiated him using a mantra for Kr̥ṣṇa worship. After this meeting Viśvambhara abandoned all scholarly and domestic pursuits and had no interests except for an intense desire to hear and speak of Krishna. Within a year he took a vow of saṃnyāsa (renunciation) and changed his name to Kr̥ṣṇa Caitanya under his guru Keśava Bhāratī. His mother then asked him to at least live in the city of Puri so that he would not be too far from Bengal.