Benjamin Castleman (born May 17, 1906, Everett, Massachusetts; died 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 authored or co-authored over 100 scholarly papers on a variety of disorders.