John Keith Laumer (June 9, 1925 – January 23, 1993) was an American science fiction author. Prior to becoming a full-time writer, he was an officer in the United States Air Force and a diplomat in the United States Foreign Service. His older brother March Laumer was also a writer, known for his adult reinterpretations of the Land of Oz (also mentioned in Laumer's THE OTHER SIDE OF TIME). Frank Laumer, their youngest brother, is a historian and writer.

Keith Laumer is best known for his Bolo and Retief stories. Stories from the former chronicle the evolution of super tanks that eventually become self-aware through the constant improvement resulting from centuries of intermittent warfare against various alien races. The latter deals with the adventures of a cynical spacefaring diplomat who constantly has to overcome the red-tape-infused failures of people with names like Ambassador Grossblunder. The Retief stories were greatly influenced by Laumer's earlier career in the US Foreign Service. In an interview with Paul Walker of LUNA MONTHLY, Laumer stated, "I had no shortage of iniquitous memories of the Foreign Service."

Laumer's other adventures often included the subjects of time travel and alternate worlds, such as found in his THE OTHER SIDE OF TIME, A TRACE OF MEMORY, DINOSAUR BEACH, and the Imperium series.

Four of his shorter works received Hugo or Nebula Award nominations ("In the Queue", was nominated for both), and A Plague of Demons (1965) received a nomination for the Nebula Award for Best Novel in 1966.