Ronald Lee Ermey (March 24, 1944 – April 15, 2018) was a United States Marine Corps drill instructor and actor.

Ermey often played roles as authority figures, such as his breakout role as Senior Drill Instructor Gunnery Sergeant Hartman in Full Metal Jacket, Mayor Tilman in Alan Parker's Mississippi Burning, Bill Bowerman in Prefontaine, Sheriff Hoyt in the remake of The Texas Chainsaw Massacre, and the leader of the plastic soldiers, Sergeant, in the Toy Story films.

He hosted two programs on the History Channel: Mail Call, in which he answered viewers' questions about various military items, both modern and historical; and Lock N' Load with R. Lee Ermey, dedicated to the development of various types of weapons.

He was a candidate for the board of directors of the National Rifle Association.