Edmund Castell (1606–1686) was an English orientalist. He was born at Tadlow, in Cambridgeshire. At the age of fifteen he entered Emmanuel College, Cambridge, gaining his BA in 1624-5 and his MA in 1628. Appointed Professor of Arabic in 1666, with the full title 'Sir Thomas Adams Professor of Arabic'. He moved to St John's in 1671, because of the valuable library there. His great work, the Lexicon Heptaglotton Hebraicum, Chaldaicum, Syriacum, Samaritanum, Aethiopicum, Arabicum, et Persicum (1669), took him eighteen years to complete, working (according to his own account) from sixteen to eighteen hours a day. He employed fourteen assistants on the project, and spent £12,000, ruining himself in the process as there was little demand for his finished lexicon.