Military career:

After high school, in the midst of World War II, Johnson joined the United States Army Air Forces as an aviation cadet; upon commissioning as a Second Lieutenant, Johnson was assigned the service number 0 765 497. He flew 44 combat missions as a bombardier in B-25 Mitchell bombers. His plane was shot down in the Philippines in March 1945, during a bombing run against Japanese targets. The plane had to crash land at the port of Zamboanga. In this mission, he broke both his ankles and earned his Purple Heart. He was also awarded the Air Medal, the Good Conduct Medal, the Asiatic-Pacific Campaign Medal with three service stars, the Philippine Liberation Ribbon with one service star, and the World War II Victory Medal. He was honorably discharged with the rank of first Lieutenant on November 22, 1945. He then joined the Army Reserves and used the GI Bill to fund his acting studies.

Movie and television career:

He became a close friend of Audie Murphy and later appeared with him in three of his films, Column South and Tumbleweed in 1953 and Ride Clear of Diablo in 1954. Johnson's Hollywood career began in 1952, with the college fraternity hazing exposé For Men Only, and with Loan Shark, also released in 1952 and starring George Raft. His early roles were primarily in westerns and science fiction such as It Came from Outer Space (1953), This Island Earth (1955), Attack of the Crab Monsters (1956), and The Space Children (1958). He also appeared in a Ma and Pa Kettle vehicle, Ma and Pa Kettle at Waikiki (1955).

During the 1950s, he guest starred on Rod Cameron's syndicated crime drama, City Detective. He appeared three times as the character "Beach" on the syndicated military drama The Silent Service, based on actual stories of the submarine section of the United States Navy. Johnson was cast as Hugh Grafton and as Tom Richards in two 1960 episodes, "Intermission" and "The Desperate Challenge", both with June Allyson on her CBS's anthology series, The DuPont Show with June Allyson. On September 16, 1963, Johnson appeared in the series premiere of the ABC medical drama Breaking Point starring Paul Richards and Eduard Franz.

Russell Johnson on The Twilight Zone:

Johnson appeared in two episodes in The Twilight Zone. He attempted to prevent the assassination of Abraham Lincoln in "Back There". He appeared as a college professor in the episode, "Execution".

Outer Limits episode:

He appeared as a crew member at the rank of major, on a U.S. space station in "Specimen: Unknown."

"The Professor" on Gilligan's Island

He is best known for playing Roy Hinkley (usually referred to as "The Professor"), the erudite polymath who could build all sorts of inventions out of the most rudimentary materials available on the island, but, as Johnson himself pointed out, could not fix the hole in the boat. Gilligan's Island aired from 1964 to 1967, but has been shown in reruns continuously ever since.

Johnson was asked to take off his shirt when auditioning for the Gilligan's Island role; he refused, but still got the job. Before accepting the role of Roy Hinkley, he made Gilligan's Island producer Sherwood Schwartz promise him that when he made scientific statements they would be accurate.

After Gilligan's Island:

After Gilligan's Island, he appeared in several other movies and television shows, especially the latter. He appeared in several dramatic series, including The Invaders, Death Valley Days, Lassie, Ironside, The F.B.I., and Gunsmoke. Perhaps most notably the miniseries Vanished, based on a novel by Fletcher Knebel (1971), uncredited in the Robert Redford spy thriller, Three Days of the Condor (1975), and on the NBC soap opera Santa Barbara.

In an interview with Starlog magazine in the early 1980s, Johnson expressed an interest in appearing on Star Trek, during its original run on NBC(1966–1969), although this did not come about. An episode of Newhart featured the Beavers (a men's organization) watching a Gilligan's Island episode on TV. When they are suddenly evicted from the room, one of them, portrayed by Johnson, protests, "I want to see how it ends!" He is assured that the castaways don't get off the island.

Johnson entertained fans at the 1996 MST3K ContevtioConExpoFest-a-Rama 2: Electric Boogaloo on the "Celebrity Panel". Johnson was invited for his role in the movie-within-a-movie of Mystery Science Theater 3000: The Movie, This Island Earth, but spent most of the time answering questions about his Gilligan's Island days.