Theodor Heinrich Boveri (12 October 1862 β 15 October 1915) was a German zoologist, comparative anatomist and co-founder of modern cytology. He was notable for the first hypothesis regarding cellular processes that cause cancer, and for describing chromatin diminution in nematodes. His brother was industrialist Walter Boveri. Boveri was married to the American biologist Marcella O'Grady (1863β1950). Their daughter Margret Boveri (1900β1975) became one of the best-known journalists in post-World War II Germany.