Swiss neuroanatomist, psychiatrist, and entomologist known for his investigations of brain structure.

Forel studied medicine at the University of Zürich from 1866 to 1871 and then did work in neuroanatomy at the University of Vienna, where he received his medical degree in 1872. In 1879 he was appointed director of the Burghölzli Asylum in Zürich and professor of psychiatry at the University of Zürich. His first major contribution to the anatomy of the brain was his paper (1877) on the tegumental region, which described various previously unknown brain structures. In 1887 he published one of his most important works, on the neuron theory, describing those cellular functional units within the brain. In 1889 he founded an institute at Zürich for the medical treatment of alcoholism, and throughout his career he worked for social reforms to prevent such causes of mental illness as syphilis and alcoholism. Forel retired in 1893 and devoted the remainder of his life to social reform and the study of the psychology of ants.