Warren Henry Manning (November 7, 1860–February 5, 1938) was an American landscape designer and promoter of the informal and naturalistic "wild garden" approach to garden design. In his designs, Manning emphasized pre-existing flora through a process of selective pruning to create a "spatial structure and character." (Karson, 1997) An advocate for the conservation of the American landscape, Manning was a key figure in the formation of the American Society of Landscape Architects and a proponent of the National Park System.