Major Warren Frederick Martin Clemens was a real-life Scottish coastwatcher who is featured in Medal of Honor: Rising Sun.
He appears in the level, Pistol Pete Showdown in a minor role. Clemens meets with Cpl. Joseph Griffin after the latter managed to fight through some parts of the jungle with Brooks and Thomason. When they encounter a POW camp, Clemens and some natives help free the prisoners being tortured, including Lt. Edmund Harrison. The group then splits up, with Griffin and Harrison going to take out Pistol Pete, which they succeed in doing, and Martin Clemens could be seen on the other side of a bridge. After the bridge is blown up, Clemens tries to lead Griffin to another mission, but is interrupted by GySgt. Lauton and Col. Floyd, who reassign Griffin to the OSS.
- An interview with the real Martin Clemens is unlockable in the game.
- A Chindit operative in the mission In Search of Yamashita`s Gold has the same model as Clemens. However, he is later killed in the mission.
- Together with Merritt Edson and Evans Carlson, Clemens is the only real person in the series.