Corporal Walter Eugene “Radar” O’Reilly is a fictional character in the M*A*S*H novels, film, the television series, the television movie W*A*L*T*E*R and two episodes of the series After M*A*S*H. The character was portrayed by Gary Burghoff in both the film and on television — the only actor from the film to reprise his role on television, aside from G. Wood as General Hammond, and the never-seen PA announcer voiced by Sal Viscuso (though this is debatable).


The novel establishes that Radar was from Ottumwa, Iowa, and literally dreamed of joining the army right after high school. He was endowed with extra-sensory perception, appearing at his commander’s side before being called and finishing his sentences. He also had super-human hearing, able to hear incoming helicopters before anyone else. It was these abilities which earned him the nickname "Radar."

His father, who had been 63 when Radar was born, was deceased. Radar's mother Edna lived on the family farm and his Uncle Ed helped out on the farm and served as his father figure.

According to the beginning of the novel, Radar joined the Army in hopes of becoming successful in the Signal Corps, but was assigned to be an orderly in a Mobile Army Surgical Hospital (M*A*S*H) instead.


On television, Radar's character started off worldly and sneaky, a clerk who carried with him at all times a pocketful of passes for any potential scam that might arise. He was known for his tremendous appetite for heaping portions of meat. He was also not averse to drinking Col. Blake's brandy and smoking his cigars when the colonel was off-duty. This character was apparently not wholly to the writers' liking and he became a naïve and trusting farm boy, a vegetarian, and cigars and strong liquor made him ill or dizzy. His favorite beverage was a grape Nehi (non-alcoholic).

Relationship With OthersEdit

Radar was often portrayed as a friendly but very young man from the Midwest. As a symbol of how young this man was when he got to Korea, he slept with a teddy bear. He related well to children and sometimes spent time with the Korean orphans in the area. He was a virgin and very naive around matters of love, making him an occasional romantic target of the camp's nurses.

Cpl. O'Reilly had a rough start as clerk at the 4077th, where it seemed he couldn't do anything right. The unit's commander, Lt. Col. Henry Blake, took him under his wing. Eventually, the young man became an excellent clerk, often balancing out Lt. Col. Blake's occasional silliness, with the near-magical abilities to get whatever the unit needed. Throughout much of the series he was more or less the glue that held the 4077th together, keeping the unit running like a well oiled machine.

Blake and Radar grew very close, and it was Radar who tearfully announced Blake's death over the Sea of Japan. While Radar needed some time to adjust to the new Col. Potter, he eventually became very close to Potter as well. Radar was very fond of animals and raised several during his duty at M*A*S*H. For Col. Potter's anniversary, Radar gave him a horse that he, Pierce and B.J. Hunnicutt rescued. Col Potter refers to the horse as a male during this episode. Throughout the rest of the series, the horse is referred to by name, Sophie, a mare.

Radar idolized Hawkeye Pierce, but the two had a falling out after Radar was injured during a trip to Seoul, after Hawkeye convinced him to go there to lose his virginity. Overwhelmed by shock and guilt, Hawkeye spent a night binge drinking, then had to leave the O.R. the next day to throw up (which he'd never had to do before). When Radar questioned Hawkeye about this, Hawkeye blew up: "To hell with your Iowa naïveté... and while we're at it, the hell with you! Why don't you grow up... you ninny?!". When Hawkeye returned to apologize, Radar's response was, much to the horror of the nurses, "Oh yeah? Well you can forget it. Just forget it! To hell with me, huh? To hell with you! How do you like that?!" and then threatened to punch Hawkeye if he ever said anything bad about Iowa again. The two made up later at Col. Potter's prompting, and afterward their relationship was on more of an equal footing, with Radar outgrowing his hero worship.

Radar's short stature was a frequent source of humor during his tenure, with Hawkeye and the other doctors teasing him for his lack of height. At one point, Radar actually bought shoes that came with lifts so that he could appear taller. The shoes almost made him eye level with Major Frank Burns.

Under Col. Potter, his scrounging and semi-legal activities are strongly curtailed, seemingly out of respect for his commanding officer.

Radar's given first name is revealed in the series when he asks a patient, who believes he is Jesus Christ, to bless his teddy bear. He then blesses Radar, who corrects him with "Walter."

Leaving M*A*S*HEdit

In the first three seasons of M*A*S*H, Gary was in every episode of the season. After season three, doing the series became a strain on Gary's family life, and had his contract changed to only doing 13 episodes per season out of the usual 24 (during these times, the character of Radar was usually on R&R). By season 7, Gary started experiencing burn-out and decided it was time to move on, despite co-star Mike Farrell trying to persuade him to stay on the grounds that his career would not recover. Because of that, the producers originally planned to end season 7 with Radar leaving, but CBS didn't want to do that. Instead they wanted Gary to come back during season 8 to do a special 2-part goodbye show. In that scenario, Radar was given a hardship discharge after his Uncle Ed died so that he could go home and help out on the farm. When the unit is in dire straits because they have no working generators, Radar decides that the 4077th needs him more than his mother does. Pierce and Potter try to convince Radar that he is making a mistake, but it takes Klinger's swindling a generator from supply to convince him that the 4077th will survive without him. As a way of saying that Radar came to Korea as a boy and went home a man, he left his teddy bear behind (as Dr. Sidney Freedman predicted he would in the episode "War of Nerves"), leaving it with Pierce. (The first cast member of M*A*S*H to be hired, Gary Burghoff was the fourth and last to leave, following the departures of McLean Stevenson and Wayne Rogers in 1975, and Larry Linville in 1977.)

Radar was referred to several time since leaving. On the next episode after leaving, Peg Hunnicutt writes BJ and says that their daughter Erin saw Radar at the airport in San Francisco and said, "Is that Daddy?" BJ was devastated that the first person to be called "Daddy" by his daughter was someone else. Once, when a young Korean farmer lost his family, the gang sent him to Iowa to work on Radar's farm. After hard times hit the farm, Radar took up a second job, working in the town's general store, as well as working the farm.

In the 1984 television movie W*A*L*T*E*R, Radar moves to St. Louis, Missouri, leaving Ottumwa, Iowa, and the "Radar" nickname behind (now just being known as Walter O'Reilly), and joins the police department. Set in the mid-1950's, his mother had died recently, and he had sold the family farm. In St. Louis, his gentle manner and resourcefulness make him good at dealing with the public. However, the show was never picked up as a regular series.

Teddy BearEdit

Radar's teddy bear had originally been found on the set by one of the actors. Throughout the series, Radar was known for sleeping with a teddy bear. This was added by the creators to symbolize Radar's youth and naïveté; it was also the source of several jokes throughout the series—which collectively formed a recurring joke in itself. In the second to last episode (actually the last episode filmed), "As Time Goes By", Pierce added the teddy bear to a time capsule with several other items from the camp including Klinger's Gone with the Wind dress and a broken fan belt from a helicopter. Hawkeye said, "Let [the bear] symbolize all the boys who came over here that left as men." On July 29, 2005, the teddy bear used in the series was sold at auction for $11,800.


Big Bird of Sesame Street has a teddy bear named Radar, perhaps a tribute to Radar O'Reilly's teddy bear & Radar O'Reilly himself.

Stargate SG-1 features a bespectacled NCO who is frequently responsible for keeping the show's main characters in operation, USAF Chief Master Sergeant Walter Harriman, played by Gary Jones. He was given the first name "Walter" in season four, which is generally assumed to be an homage to O'Reilly.

Radar was only in his late teens, but Gary Burghoff himself was almost 30 at the time the series began. Audiences were generally fooled by his short stature, boyish appearance and prepubescent voice.

Gary Burghoff's left hand is slightly (but visibly) deformed, which would ironically make him unfit for military service. This was covered up in the series by Radar holding a prop such as a clipboard in that hand or simply putting it in his pocket.

Having played the character in the feature film, the television series and two of its spin-offs, Gary Burghoff is the only actor to portray Radar. Trapper John, M.D. is the only version or spin-off of M*A*S*H in which Burghoff does not appear.

O'Reilly Media maintains a blog about new technologies entitled O'Reilly Radar, which has the domain name

With Radar's departure from the show, Hawkeye Pierce, Margaret Houlihan and Father Mulcahy were the only remaining characters on the M*A*S*H TV series with ties to the 1968 novel and the 1970 movie.

Burgoff also played Mrs. O'Reilly in one episode in a home movie, dressing in drag.

Burgoff was also the first adult actor to appear nude from the rear on broadcast television. In the episode "The Sniper", Burgoff's towel fell off too early, revealing his bare buttocks for a noticeable amount of time.


  • "Lt. Col. Henry Blake's plane was shot down, over the Sea of Japan. It spun in. There were no survivors."
  • "Animals are people too!"
  • "I'm not short. I'm not."