Benjamin Castleman (May 17, 1906, Everett, Massachusetts – June 29, 1982, Boston, Massachusetts) was an American physician and pathologist best known for describing Castleman's disease (angiofollicular lymphoid hyperplasia), which is named after him. He was also one of the authors of the first case series on pulmonary alveolar proteinosis in a 1958 article in the New England Journal of Medicine. ("Rosen–Castleman–Liebow syndrome" is a rarely used term for that condition.) Castleman undertook clinicopathologic investigations of parathyroid disease and wrote several important papers on diseases of the thymus and mediastinum. He wrote, or collaborated in writing, over 100 scholarly papers on a variety of disorders.