Florence Parry Heide (born February 27, 1919) is a bestselling American children's writer. Born in Pittsburgh and spending most of her childhood in Punxsutawney, Pennsylvania, she studied at Wilson College in Chambersburg, PA. After two years, she transferred to UCLA and graduated in 1939. She worked in advertising and public relations in New York City before returning to Pittsburgh during World War II and became publicity director of The Pittsburgh Playhouse. She met her husband, Capt. Donald C. Heide, in October, 1943. They married six weeks later, on November 27, 1943.

After the war ended, she and her husband moved to Kenosha, Wisconsin. He began a private law practice where he worked until his retirement in 1982. She devoted herself to her children and began her career as a children's author during the 1960s while they were still at home. Her first book, Maximilian, was published in 1967. She has since published more than 100 books for children and youth - from picture books to adolescent novels - and several collections of poetry. She also collaborated with Sylvia Van Clief to write a number of songs. Her best known works are a series of story books about the curious adventures of a boy named Treehorn, which includes the titles The Shrinking of Treehorn (1971), Treehorn's Treasure (1981) and Treehorn’s Wish (1986), all of which Edward Gorey illustrated. She has also worked with renowned illustrators Jules Feiffer and Lane Smith and has won numerous awards for her work. She is the mother of five children including authors Judith Heide Gilliland and Roxanne Heide Pierce, with whom she has co-written several other critically acclaimed books. She has seven grandchildren and a growing number of great-grandchildren.

Heide was well known in Kenosha for the Fourth of July parade she organized each year: hundreds of children with their bikes decorated would gather outside her home and ride twice around her block to the beat of a drum. Although she has since moved, the parade continues each year in her honor.