Katharine Jeanette Bush (December 30, 1855 – 1937) was an American zoologist.
She was born in Scranton, Pennsylvania, and was educated in the public and private schools of New Haven, Connecticut. In 1901, she became the first woman to receive a Ph.D. in the sciences at Yale University.
Bush studied zoology under A. E. Verrill and in 1879 assumed the position of assistant in the zoological museum at Yale University. She served on the United States Fish Commission, helped to edit the 1890 edition of Webster's dictionary, and was made a member of the American Society of Naturalists and the American Society of Zoologists. She wrote "The Tubicolous Annelids of the Tribes Sabellides and Serpulides," in Harriman Alaska Expedition, volume xii (1905), besides Deep Water Mollusca (1885) and New Species of Turbonilla (1899).