Harry Morgan, 96, who won an Emmy Award playing the tough but fair Col. Sherman T. Potter on the comedy series “M*A*S*H” and was a supporting actor for six decades in movies and on television, died Dec. 7 at his home in Los Angeles.

He had pneumonia, said his son Charles Morgan.

Mr. Morgan — billed as Henry Morgan for much of his early career — was slight and balding and had a gravelly voice that could convey menace, irritation or wryness. Such versatility kept him in near-constant demand as a performer, and he became an instantly recognizable screen personality.

He had appeared in more than 100 films since the 1940s and was particularly effective as a witness to a lynching of alleged cattle rustlers in “The Ox-Bow Incident” (1943); a shadowy villain in “The Big Clock” (1948); a businessman who fears outlaws in “High Noon” (1952); and a small-town judge in “Inherit the Wind” (1960), based on the Scopes Monkey Trial.

Starting in the early 1950s, Mr. Morgan was a frequent movie sidekick to James Stewart in westerns (“Bend of the River,” “The Far Country”) and military dramas (“The Mountain Road,” “Strategic Air Command”). He also played pianist Chummy MacGregor in the 1953 musical biography of Glenn Miller, the swing bandleader portrayed by Stewart.

On television, Mr. Morgan had been a near-constant presence since the 1950s. He received an Emmy nomination for his role as the sardonic neighbor of Spring Byington in “December Bride,” which aired on CBS from 1954 to 1959. His work led to a CBS spinoff, “Pete and Gladys,” which ran from 1960 to 1962 and featured Cara Williams as Mr. Morgan’s scatterbrained wife.

He appeared in several films with actor Jack Webb, who became a TV star and producer of the police drama “Dragnet.” In the late 1960s, Mr. Morgan replaced Ben Alexander as sidekick to Webb’s Sgt. Joe Friday on “Dragnet” and acted in several other short-lived TV dramas created by Webb’s production company.

On the small screen, Mr. Morgan was best remembered for “M*A*S*H,” a long-running sitcom set during the Korean War, and for which he won an Emmy in 1980 as Col. Potter, a crusty cavalry veteran.

In the part, he took a seen-it-all approach to his aide, Cpl. Maxwell Q. Klinger, who wore women’s clothes in his quest for a discharge for psychological unfitness. “Soldiers, I’ve seen every dodge in the book,” Potter tells Klinger in one episode. “We had a man who pretended he was a mare — carried a colt around in his arms. Another thought he was a daisy and insisted on being watered every day. Get out of that frou-frou and back into uniform, soldier.”

Mr. Morgan joined the cast of “M*A*S*H” in 1975, three years into its run, after McLean Stevenson left the show. Mr. Morgan later told Parade magazine: “I don’t know just why they called me, to be perfectly frank. In the third year, I played a sort of crazy general in one episode, and they liked me.”

The last episode of “M*A*S*H,” in 1983, drew what was widely reported at the time to be the largest audience to watch a single TV program.

He reprised the part of Col. Potter for a short-lived sequel, “AfterMASH,”which took place at a veterans’ hospital in Missouri. Afterward, Mr. Morgan starred in the NBC drama “Blacke’s Magic” (1986) — as the father of a magician-detective played by Hal Linden — and made guest appearances on dramas and sitcoms through the 1990s.

Harry Bratsburg was born April 10, 1915, in Detroit, where his Norwegian-born father was a mechanic. He grew up in Muskegon, Mich.

He excelled in high school debate and, hoping to be a lawyer, took oratory classes at the University of Chicago. He left school during the Depression and sold office furniture in Washington.

As a hobby, he found work with Washington theater troupes and by 1937 was part of the Group Theatre in New York, which included Elia Kazan, John Garfield and Karl Malden. With that company, he appeared several times on Broadway in minor parts, notably in two Clifford Odets plays, “Golden Boy” and “Night Music,” as well as Irwin Shaw’s “The Gentle People” and Robert Ardrey’s “Thunder Rock.”

Mr. Morgan remained Harry Bratsburg in his early stage career but was known as Henry Morgan through the 1950s. Afterward, he regularly began using Harry Morgan to avoid confusion with a popular radio and TV entertainer named Henry Morgan (1915-1994).

Still billed as Henry Morgan, he made his film debut in the wartime drama “To the Shores of Tripoli” (1942). He said Henry Fonda got him a part in his best-known early film, “The Ox-Bow Incident,” after they appeared together in a stage version of Owen Wister’s novel “The Virginian.”

In other early film roles, Mr. Morgan appeared in war dramas (“A Bell for Adano”) and musicals (“State Fair”). His later movie parts included Gen. Ulysses S. Grant in “How the West Was Won” (1962) and the mayor in the farcical western “Support Your Local Sheriff!” (1969) with Joan Hackett as his daughter.

After the success of “December Bride,” more sitcom work followed. Mr. Morgan’s appearance in “The Richard Boone Show” was significant because he began to learn directing from Boone. Mr. Morgan went on to direct episodes of the Webb-produced cop show “Adam-12,” as well as “M*A*S*H.”

His first wife, actress Eileen Detchon Morgan, whom he married in 1940, died in 1985. A son from that marriage, Daniel Morgan, died in 1989.

Survivors include his wife since 1986, Barbara Bushman Quine, granddaughter of silent-film star Francis X. Bushman; three sons from his first marriage, Chris Morgan of New Orleans and Charles Morgan and Paul Morgan, both of Los Angeles; and eight grandchildren.

During his long acting career, Mr. Morgan showed a flair for deadpan comic delivery. In “Support Your Local Sheriff!,” he talks about his daughter to the sheriff, played by James Garner.

“She takes after her dear, departed mother,” Mr. Morgan says.

“Her mother is dead?” asks Garner.

“No. She just departed.”