Arthur Dendy (Manchester, 20 January 1865 – 24 March 1925, London) was an English zoologist known for his work on marine sponges and the terrestrial invertebrates of Victoria, Australia, notably including the "living fossil" Peripatus. He was in turn professor of zoology in New Zealand, in South Africa and finally at King's College London. He was a Fellow of the Royal Society.
Dendy's parents were John Dendy, a silk fabric maker of Manchester, and Sarah Beard. His sisters included Mary Dendy and Helen Bosanquet. He married Ada Margaret Courtauld on 5 December 1888. They had four children, three daughters and one son.
He was educated in zoology at Owens College, Manchester, gaining his M.Sc. in 1887 and his D.Sc. in 1891. He worked on part of the report of the Challenger expedition (1872–1876), describing monaxonid sponges. In 1888 he moved to the University of Melbourne as demonstrator and assistant lecturer. There he identified and described almost 2000 specimens of sponges from the sea near Port Phillip Heads. This work led to ten scientific papers on Australian sponges; he described 87 new species of sponge. Eventually Dendy became a leading authority on the sponge phylum, (Porifera), which he extensively restructured.
Dendy was the first zoologist to study the terrestrial invertebrates of Victoria, Australia. This work led to 16 scientific papers and 79 new species. These included terrestrial flatworms (planarians) and nemerteans, but the most famous of his animals was the so-called "living fossil" Peripatus.
In 1893, Dendy became professor of biology at Canterbury College, Christchuch, New Zealand.
In 1903, Dendy became professor of biology at the University of Cape Town, South Africa.
In 1905, Dendy became professor of zoology at King's College, London.