Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura (1874–1937) was one of the most influential teachers of modern Gauḍīya Vaiṣṇavism and a major force in the revival and organized propagation of the mission of Śrī Caitanya Mahāprabhu. Born as Bimala Prasāda Datta in Jagannātha Purī, he was the son of Śrīla Bhaktivinoda Ṭhākura, whose writings and preaching helped restore the intellectual and devotional vitality of the Gauḍīya tradition. From an early age, Bhaktisiddhānta Sarasvatī displayed exceptional dedication to the study of the Śāstras, strict spiritual discipline, and devotion to Kṛṣṇa. He received spiritual initiation from Śrīla Gaura Kiśora Dāsa Bābājī Mahārāja, a saint renowned for profound renunciation and absorption in Bhajana. Bhaktisiddhānta Sarasvatī united this contemplative heritage with an energetic missionary vision. He taught that genuine renunciation does not mean merely rejecting the material world, but engaging everything—knowledge, technology, institutions, wealth, printing presses, and personal ability—in the service of Śrī Kṛṣṇa. He founded the Gauḍīya Maṭha and established numerous centers for the teaching of Bhāgavata-dharma. He placed extraordinary emphasis on publishing books, periodicals, and theological works. He famously regarded the printing press as a Bṛhat-mṛdaṅga, a “great mṛdaṅga” whose sound could carry the message of Śrī Caitanya Mahāprabhu far beyond the reach of an ordinary drum. His teachings strongly emphasized Śuddha-bhakti, pure devotion free from material ambition and impersonal speculation. He challenged hereditary conceptions of spiritual authority and argued that genuine Vaiṣṇava qualification rests upon devotion, realization, character, and fidelity to Guru-paramparā, rather than birth alone. Among his disciples was Śrīla A. C. Bhaktivedanta Swami Prabhupāda, whom he strongly encouraged to preach the teachings of Kṛṣṇa-bhakti in English. Through this disciplic connection, Bhaktisiddhānta Sarasvatī’s missionary vision later expanded across the world. His legacy remains closely associated with uncompromising fidelity to the Śāstras, devotion to Hari-nāma, service to the spiritual master, and the dissemination of devotion to Rādhā-Kṛṣṇa.