Anil Kumar Gain (1 February 1919 – 7 February 1978) (also spelt Anil Kumar Gayen) was an Indian mathematician and statistician best known for his works on the Pearson product-moment correlation coefficient in the field of applied statistics, with his colleague Ronald Fisher. He received his Ph.D. from the University of Cambridge under the supervision of Henry Ellis Daniels, who was the then President of the Royal Statistical Society. He was honoured as a Fellow of the Royal Statistical Society and the Cambridge Philosophical Society.