Mordecai Cubitt Cooke (12 July 1825 in Horning – 12 November 1914 in Southsea, Hants) was an English botanist and mycologist.
Cooke came from a mercantile family in Horning, Norfolk, and worked as an apprentice to a fabric merchant before becoming a clerk in a law firm, but his chief interest was in botany. He founded the Society of Amateur Botanists in 1862. He taught natural history at Holy Trinity National School, Lambeth, and worked as a curator at the India Museum at India Office from 1860 to 1879. In 1879 when the botanical collections from the India Museum were transferred to the Royal Botanic Gardens, Kew, Cooke went with them. He received the Victoria Medal of Honour from the Royal Horticultural Society in 1902 and the Linnean Medal from the Linnean Society of London in 1903.
He was awarded several honorary diplomas for his work, primarily with fungi, a Master of Arts from St. Lawrence University in 1870, a Master of Arts from Yale University in 1873 and a doctorate from the New York University.
Cooke took part in the publication, together with Edward Step (1855–1931), of the monthly magazine Hardwicke's Science-Gossip: A Monthly Medium of Interchange and Gossip for Students and Lovers of Nature from 1865 to 1893. From 1872 to 1894 Cooke also edited, Grevillea, a monthly record of cryptogamic botany and its literature, a periodical devoted to the study of mushrooms. He was one of the founders of the Quekett Microscopical Club in 1865, in response to a request in Science Gossip.