Bhaktisiddhanta Sarasvati Thakura, Indian religious leader, founded the Gaudiya Math (d. 1937)
Bhaktisiddhanta Sarasvati (IAST: Bhakti-siddhānta Sarasvatī; Bengali: ভক্তিসিদ্ধান্ত সরস্বতী; Bengali: [bʱɔktisiddʱanto ʃɔrɔʃbɔti] (listen); 6 February 1874 – 3 January 1937), born Bimala Prasad Datt (Bimalā Prasāda Datta, Bengali: [bimola prɔʃɑd dɔtto]), was a Gaudīya Vaisnava Hindu guru (spiritual master), ācārya (philosophy instructor), and revivalist in early 20th century India. To his followers, he was known as Srila Prabhupāda (an honorific also later extended to his disciple A. C. Bhaktivedanta Swami Prabhupada).

Bimala Prasad was born in 1874 in Puri (Orissa) in a Bengali Hindu Kayastha family as a son of Kedarnath Datta Bhaktivinoda Thakur, a recognised Bengali Gaudiya Vaishnava philosopher and teacher. Bimala Prasad received both Western and traditional Indian education and gradually established himself as a leading intellectual among the bhadralok (Western-educated and often Hindu Bengali residents of colonial Calcutta), earning the title Siddhānta Sarasvatī ("the pinnacle of wisdom"). In 1900, Bimala Prasad took initiation into Gaudiya Vaishnavism from the Vaishnava ascetic Gaurkishor Dās Bābājī.In 1918, following the 1914 death of his father and the 1915 death of his guru Gaurakisora Dasa Babaji, Bimala Prasad accepted the Hindu formal order of asceticism (sannyasa) from a photograph of his guru and took the name Bhaktisiddhanta Saraswati Goswami. Bhaktisiddhanta Saraswati inaugurated in Calcutta the first center of his institution, later known as the Gaudiya Math. It soon developed into a dynamic missionary and educational institution with sixty-four branches across India and three centres abroad (in Burma, Germany, and England). The Math propagated the teachings of Gaudiya Vaishnavism by means of daily, weekly, and monthly periodicals, books of the Vaishnava canon, and public programs as well as through such innovations as "theistic exhibitions" with dioramas. Bhaktisiddhanta is known for his intense and outspoken oratory and writing style as the "acharya-keshari" ("lion guru"). Bhaktisiddhanta opposed the monistic interpretation of Hinduism, or advaita, that had emerged as the prevalent strand of Hindu thought in India, seeking to establish traditional personalist krishna-bhakti as its fulfillment and higher synthesis. At the same time, through lecturing and writing, Bhaktisiddhanta Saraswati Prabhupāda targeted both the ritualistic casteism of smarta brahmanas and sensualised practices of numerous Gaudiya Vaishnavism spin-offs, branding them as apasampradayas – deviations from the original Gaudiya Vaishnavism taught in the 16th century by Chaitanya Mahaprabhu and his close successors. Ironically, the same accusations are also levelled at the Gaudiya Math institutions, namely that they are an apasiddhanta line.

The mission initiated by Bhaktivinoda Thakur and developed by Bhaktisiddhanta Saraswati Goswami Prabhupāda emerged as "the most powerful reformist movement" of Vaishnavism in Bengal of the 19th and early 20th century. However, after the demise of Prabhupāda in 1937, the Gaudiya Math became tangled by internal dissent, and the united mission in India was effectively fragmented. Over decades, the movement regained its momentum. In 1966 its offshoot, the International Society for Krishna Consciousness (ISKCON), was founded by Prabhupāda's disciple Bhaktivedanta in New York City and spearheaded the spread of Gaudiya Vaisnava teachings and practice globally. Prabhupāda's branch of Gaudiya Vaishnavism presently counts over 500,000 adherents worldwide, with its public profile far exceeding the size of its constituency.