Walter Medley Tattersall (8 November 1882 – 5 October 1943) was a British zoologist and marine biologist, famous for his study of mysids.
He was born in Liverpool, the eldest son of a draper's family. He studied zoology at the University of Liverpool, where he graduated in 1901. Subsequently, he worked as a naturalist for the Irish Fisheries Department under Ernest William Lyons Holt, where he began his studies of crustaceans.