John F. Slade III (born August 5, 1943) is an Associate Judge with the 4th District Court of Maryland. Slade served in the Maryland House of Delegates from 1983 to 2003. He represented District 29C, which represented part of St. Mary's County, from 1983 to 1994 and represented District 29B, which represented parts of Calvert County and St. Mary's County, from 1995 to 2002.