Karlheinz Bohm, shown here with actress Anna Massey in the film “Peeping Tom,” died May 29 at 86. (Rialto Pictures and Studiocanal)

Karlheinz Böhm, an actor who was best known for his portrayal of Emperor Franz Joseph in a gauzy 1950s film series about the Austrian court, and then stunned audiences with his disarming portrayal of a psychopathic killer in the now-classic thriller “Peeping Tom,” died May 29 at his home near Salzburg, Austria. He was 86.

His death was announced by Menschen für Menschen, or “People for People,” an Ethio­pian aid and development organization that Mr. Böhm founded and led for decades after retiring from acting. German media reported he had Alzheimer’s disease.

Mr. Böhm was the only son of the acclaimed Austrian conductor Karl Böhm and the German soprano Thea Linhard. He began his acting career on stage and became widely popular in postwar Europe when he was cast as the Austrian emperor in movies featuring Romy Schneider as Empress Elisabeth, or “Sissi.”

Lighthearted and romantic, the “Sissi” series remained an audience favorite for generations and established the blond, handsome Mr. Böhm as a movie idol.

Then came the release in 1960 of “Peeping Tom,” which featured Mr. Böhm as a film technician who, outside the studio, murders women in ritualistic killings that he records on camera to capture his victims’ fear.

After his acting career, Mr. Bohm, shown here in 2008, founded and led an aid organization dedicated to development work in Ethi­o­pia. (Johannes Simon/Getty Images)

The film was the work of British director Michael Powell and also featured Moira Shearer, the actress who had played the tortured ballerina in “The Red Shoes” (1948), a drama that helped establish Powell as a major cinematic talent.

“Peeping Tom” made innovative use of color and camera techniques and achieved what has been described as extreme terror. Viewers are enticed to feel sympathy for Mr. Böhm’s character, Mark Lewis, when they learn that he was the subject of his father’s psychological experiments about the inducement of fear.

(The film’s release came months before the opening of a film that would become a more noted psychodrama — Alfred Hitchcock’s “Psycho” — and the coincidence led to comparisons over the years. A writer in the Edmonton Journal of Canada once noted that Mark Lewis’s “social skills make ‘Psycho’s’ Norman Bates look like John F. Kennedy.”)

Initially “Peeping Tom” was excoriated by critics. One explanation was that they and film industry insiders were offended by the movie’s juxtaposition of moviemaking and voyeurism.

“I have carted my travel-stained carcass to some of the filthiest and most festering slums of Asia,” one critic in England opined, “but nothing, nothing, nothing — neither the hopeless leper colonies of East Pakistan, the back streets of Bombay nor the gutters of Calcutta — has left me with such a feeling of nausea and depression as I got this week while sitting through a new British film called ‘Peeping Tom.’ ”

Mr. Böhm recalled a “deadly silence” at the film’s opening.

“It hurt me at least as much as Mickey Powell,” he said, referring to the director in the documentary , “A Very British Psycho,” about the making of the film.

The disapproving critics, wrote New York Times film reviewer Janet Maslin, later “ate crow.”

In part through promotion by admirers including director Martin Scorsese, the film experienced a revival and today it is widely regarded as a masterpiece.

Mr. Böhm’s “performance creates a vicious killer who is shy and wounded,” critic Roger Ebert wrote in the Chicago Sun-Times. “The movie despises him, yet sympathizes with him. He is a very lonely man.”

In the 1960s, Mr. Böhm played Jacob Grimm in “The Wonderful World of the Brothers Grimm,” portrayed composer Ludwig van Beethoven in Disney’s “The Magnificent Rebel” and appeared as a fascist sympathizer in director Vincente Minnelli’s “The Four Horsemen of the Apocalypse.” In the 1970s, he appeared in several films by the German director Rainer Werner Fassbinder, whom Mr. Böhm credited with inspiring his interests in global affairs.

“I considered him to be the most interesting political critic of the time,” he once said, according to Deutsche Welle World.

In the 1980s, Mr. Böhm made an abrupt career change. Appearing on a German-language entertainment television program, he was asked to make a wager.

“I bet that not one-third of viewers would give one Deutsche mark, one Swiss franc, seven Austrian schillings for the people suffering in the Sahel region,” he said, referring to the drought-prone region of Africa.

Mr. Böhm’s pessimism was unfounded. The program reportedly raised hundreds of thousands of dollars and led Mr. Böhm to form Menschen für Menschen, which he led from 1981 until 2011, and which funded the development of hospitals, schools and training centers in Ethi­o­pia, among other work.

Karlheinz Böhm — his first name was at times abbreviated Karl or Carl — was born March 16, 1928, in Darmstadt, Germany, and he grew up traveling through Europe for his father’s musical career.

The elder Böhm was regarded as one of the greatest conductors of his generation. Ebert wrote that when casting the younger Böhm in “Peeping Tom,” Powell, the director, was intrigued by the actor’s lineage.

“He might know something of overbearing fathers,” Ebert observed.

During World War II, Mr. Böhm attended a boarding school in Switzerland. He studied philosophy and philology at the University of Graz in Austria before beginning his acting career. In addition to his film work, he directed operas for a period.

A complete list of his marriages and survivors could not immediately be confirmed. His wife, Almaz, succeeded him as chair of Menschen für Menschen in 2011.

Mr. Böhm, who was widely honored for his development work, once explained what inspired him to change lines of work.

“If you think how many lives you could save,” the Deutsche Presse-Agentur agency quoted him as saying, “a single one is more important than the greatest success you could ever have on a stage.”