Srinivasa Ramanujan is universally regarded as a master of number theory. Despite having little formal training, he made extraordinary contributions to mathematical analysis, number theory, infinite series, and continued fractions. His work on partitions, prime numbers, and modular forms revolutionized the field. Meghnad Saha was an astrophysicist, J.C. Bose was a biologist/physicist, and C.V. Raman was a physicist.