Sir Edward Leithen is a fictional character in several of John Buchan's novels: The Power-House, John Macnab, The Dancing Floor, The Gap in the Curtain and Sick Heart River. These were published over a number of years, the first in 1916 (although "The Power House" was originally published in a magazine in 1913), and the last in 1941, one year after Buchan's death. Leithen's name is borrowed from the Leithen Water, a tributary of the River Tweed, one of many references to the Scottish Borders in Buchan's novels.
He also appears in The Return of John MacNab by Andrew Greig in a 1990s retelling of John Macnab.