Arbus was born in New York City to stockbroker Harry Arbus and his wife Rose (née Goldberg). He attended DeWitt Clinton High School in the Bronx, where he first developed an interest in acting while appearing in a student play. Arbus was also a music lover. Before becoming an actor, he was reportedly so taken by Benny Goodman’s recordings that he took up playing the clarinet.
During the 1940s, Arbus became a photographer for the United States Army. In 1946, after completing his military service, he and his first wife, the noted photographer Diane Arbus, whom he married in 1941, started a photographic advertising business in Manhattan. Arbus was primarily known for advertising photography that appeared in such publications as Glamour, Vogue, Harper’s Bazaar, and other magazines.
Following the break-up of his marriage and the dissolution of his photography business, Arbus moved to Los Angeles to pursue acting. He appeared in such films as “Putney Swope” (1969), “Greaser’s Palace” (1972), and “Cinderella Liberty” (1973), as well as guest spots on TV series such as “The Rockford Files,” “The Odd Couple,” and “Taxi.” But it was his role as the affable psychiatrist Major Sidney Freedman on “M*A*S*H” for which he is most remembered. Arbus appeared on the show a dozen times between 1973 and 1983, including the show’s landmark two-hour finale, “Goodbye, Farewell, and Amen,” which was watched by a record 130 million viewers.
After “M*A*S*H” ended, Arbus continued appearing on television in guest and recurring roles on such shows as “Cagney & Lacey, “Matlock,” and “L.A. Law.” His last TV appearance was in 2000 on Larry David’s HBO series “Curb Your Enthusiasm.”
Allan and Diane Arbus had two children, photographer Amy Arbus and writer and art director Doon Arbus. The couple separated in 1959 and divorced in 1969, two years before Diane committed suicide.
Arbus married actress Mariclare Costello in 1977, with whom he had one daughter, Arin Arbus.