The Lieutenant is an American television series, the first created by Gene Roddenberry. An hour-long drama, it aired on NBC on Saturday evenings in the 1963–1964 television schedule. It was produced by Arena Productions, one of Metro-Goldwyn-Mayer's most successful in-house production companies of the 1960s. Situated at U.S. Marine Corps base Camp Pendleton in California, The Lieutenant focuses on enlisted Marines and officers in peacetime with a Cold War backdrop. The title character is Second Lieutenant William Tiberius Rice, a rifle platoon leader and one of the camp's training instructors.

The series involved a number of actors well known for their other roles, including several who would later appear in Roddenberry's more well known work, Star Trek. The central character—whose middle name would be shared with the character James T. Kirk—was played by Gary Lockwood, who was featured in the second Star Trek pilot "Where No Man Has Gone Before".