Encouraged by a family friend to audition for the theater and lie about his lack of experience, the red-haired, freckle-faced Mr. Lydon went into acting, despite having near seen a stage show. He made his Broadway debut that year at age 14, appearing with Van Heflin in a play called “Western Waters,” and went on to develop an acting career that spanned half a century and nearly 150 film and television credits, including on one of the first TV soap operas, “The First Hundred Years,” and on a 1987 episode of the medical drama “St. Elsewhere,” his swan song.

Mr. Lydon said he never really enjoyed being in front of the camera, and blamed Hollywood for the loss of his childhood. But he became an in-demand actor while playing kindhearted adolescents, including the British title character in “Tom Brown’s School Days” (1940) and the oldest son of William Powell and Irene Dunne in “Life With Father” (1947), a critically acclaimed Technicolor comedy. As Mr. Lydon told it, he also gave Elizabeth Taylor her first on-screen kiss while playing her love interest in “Cynthia” (1947), when he was 24 and she was 15.

Yet he remained best known for playing the endearingly gawky Henry Aldrich in a hit movie series for Paramount, emerging as a big-screen symbol of American boyhood alongside Mickey Rooney, who starred as Andy Hardy in another popular film series of the 1930s and ′40s. Summoned by his mother with a piercing cry — “Hennnnnn-reeeeeee! Hen-ry Aldrich!” — Mr. Lydon’s character would reply with a signature nasal twang and a crack in his voice: “Coming, mother!”

Mr. Lydon was 98 when he died March 9 at his home in San Diego. His daughter Cathy Lydon confirmed the death but did not give a cause.

Even as he aged-out of adolescent screen roles, Mr. Lydon was often approached by strangers who would ask, “Say, aren’t you Henry Aldrich?” He remained modest about his film career, telling the San Diego Union-Tribune, “I was the junior-flyweight king of the B pictures.”

The Henry Aldrich character originated in 1938, played by Ezra Stone on Broadway in Clifford Goldsmith’s play “What a Life” and later on the radio in a popular weekly sitcom, “The Aldrich Family.” Jackie Cooper took over the role for two movies before Mr. Lydon succeeded him on-screen, playing Henry in nine films, from “Henry Aldrich for President” (1941) to “Henry Aldrich’s Little Secret” (1944).

Mr. Lydon said he sought to avoid being typecast in the role, asking Paramount executive Y. Frank Freeman to put him in other movies outside the Henry series.

“You’re getting paid,” the studio chief replied. “Go do your work.”

He later starred in director Edgar G. Ulmer’s “Strange Illusion” (1945), a low-budget film noir inspired by “Hamlet,” and appeared in more prominent movies such as “The Time of Your Life” (1948) with James Cagney, “Joan of Arc” (1948) with Ingrid Bergman, “September Affair” (1950) with Joan Fontaine and Joseph Cotten, and “The Magnificent Yankee” (1950), starring Louis Calhern as Supreme Court Justice Oliver Wendell Holmes Jr.

Beginning in the early 1960s, he was also an associate producer on shows including the detective drama “77 Sunset Strip” and the World War II sitcom “Mister Roberts.” He later branched into TV writing and directing, and as a producer for Warner Bros. he worked on photographer and filmmaker Gordon Parks’s 1969 coming-of-age film “The Learning Tree,” considered the first major Hollywood movie directed by an African American.

Mr. Lydon was also an assistant producer of the CBS sitcom “Roll Out,” a “M.A.S.H.”-style military comedy that starred two Black actors, a rarity at the time, and ran for one season beginning in 1973. Appearing on-screen in a guest role, he played an Army captain with a familiar name: Aldrich.

The fifth of nine children, James Joseph Lydon was born in Harrington Park, N.J., on May 30, 1923. He said he had two club feet that were nearly amputated before a doctor intervened and performed corrective surgery, and walked with a slight limp for the rest of his life.

Mr. Lydon performed in five Broadway shows, including the revue “Sing Out the News,” before making his Hollywood debut in “Back Door to Heaven” (1939), kicking off what he described as a stressful period of nonstop rehearsals, tours, movie productions and television or radio appearances.

“From the very beginning, it was a very ugly experience,” he said in an interview for Richard Lamparski’s book series “Whatever Became Of…?” He later advocated for an actors’ pension and health care plan as vice president of the Screen Actors Guild.

Mr. Lydon appeared in dozens of TV guest roles, including episodes of “Maverick,” “The Twilight Zone,” “The Six Million Dollar Man” and “Lou Grant,” in addition to acting in movies such as “The Last Time I Saw Archie” (1961), a comedy with Robert Mitchum, and “Vigilante Force” (1976), with Kris Kristofferson.

His marriage to Patricia Pernetti ended in divorce. In 1952 he married Betty Lou Nedell, the daughter of actress Olive Blakeney, who played his mother in the Aldrich movies. Their daughter Cathy said in a phone interview that Blakeney celebrated the wedding by sending out cheeky cards, “saying something like, ‘My daughter is marrying my son.’ ”

His wife died New Year’s Day. In addition to his daughter Cathy Lydon, of Albuquerque, survivors include another daughter, Julie Lydon Cornell of Taplow, England; and two granddaughters.

Mr. Lydon never wanted his daughters to go into acting, telling Lamparski that it was “unnatural” to see kids on the stage or screen.

“He told us from the time I can remember that he wanted us to have a real childhood that he didn’t have,” Cathy said. “When we turned 21, if we wanted to get into the business, he would help us any way we could. By the time we were 21, we knew better.”