Ashani Tanuja Weeraratna (born 1970/1971) is a Sri Lanka-born American cancer researcher whose findings are contributing to the scientific understanding of melanoma tumors. She is a Bloomberg Distinguished Professor of cancer biology and the E.V. McCollum Professor and Chair of the department of biochemistry and molecular biology at the Johns Hopkins Bloomberg School of Public Health. Weeraratna is a member of the National Cancer Advisory Board, which advises and assists the director of the National Cancer Institute on the activities of the national cancer program.