Steve Landesberg, an actor and comedian with a friendly and often deadpan manner who appeared on television and in movies, including “Barney Miller,” “The Golden Girls,” and “Forgetting Sarah Marshall,” has died, his agent said Monday. He was 65.
The agent, Jeffrey Leavitt, confirmed the death but said he did not have details of where and when Mr. Landesberg passed away.

Mr. Landesberg is probably best known for the role of Det. Sgt. Arthur P. Dietrich on the ’70s sitcom “Barney Miller.” The sitcom, which ran on ABC from 1975 to 1982, featured Mr. Landesberg playing an intellectual detective with a quiet manner who seemed to have an unrivaled knowledge of practically any topic that arose, much to the bemusement of his fellow detectives.

The sitcom, set in a New York City police station, portrayed a group of wisecracking detectives who dealt with the oddball characters who would end up there. With most of the action in the squad room rather than out in the street, some police officers have said that the show often better represented the real life of rank-and-file officers than many detective dramas on television. Mr. Landesberg appeared occasionally during the first few seasons of the show and became a full cast member in the fourth season.

After “Barney Miller” left the air, Mr. Landesberg appeared on several other television shows, including “The Golden Girls,” “Harry and the Hendersons,” “That ‘70s Show” and “Everybody Hates Chris.” In 2008 he played Dr. Rosenbaum in the movie “Forgetting Sarah Marshall.” Most recently, Mr. Landesberg played Dr. Myron Finkelstein, a Freudian therapist, in “Head Case” a comedy on the Starz cable channel.

Born Nov. 23, 1945, in New York City, Mr. Landesberg began working in New York comedy clubs in the late 1960s and early 1970s, when he was a contemporary of such comedians as Freddie Prinze and Jimmy Walker. He appeared on “The Tonight Show” for the first time in 1971 and several times on “The Dean Martin Show” before landing his first recurring roll as Fred Meyerbach in “Paul Sand in Friends and Lovers” in 1974 and 1975.

He is survived by his wife, Nancy Ross Landesberg, and a daughter, Elizabeth.