Ensign O'Toole is an American sitcom that stars Dean Jones in the title role as an officer aboard the United States Navy destroyer USS Appleby in the early 1960s.

Ensign O'Toole is a junior officer aboard the fictional destroyer USS Appleby in the peacetime United States Navy of the early 1960s.

Also aboard the Appleby are the ship's executive officer, Lieutenant Commander Virgil Stoner; its supply officer, the rich and usually befuddled Lieutenant (junior grade) Rex St. John; and an assortment of zany crewmen, including Chief Petty Officer Homer Nelson — who always seems to be in search of a poker game and often butts heads with O'Toole — and Seamen Gabby Di Julio, Howard Spicer, and Claude White.

The nonchalant O'Toole is clever, speaks several languages, can answer any trivia question, and expresses expertise in almost any subject that comes up, but avoids doing work, preferring to spend his time pulling pranks and showing up the ambitious and overbearing St. John, usually with the enthusiastic help of the crew.

[5] Prime-time reruns of Ensign O'Toole followed in its regular time slot on NBC until September 15, 1963.