Emmanuelle Riva, in her Oscar-nominated role as Anne in the 2012 film “Amour.” (Darius Khondji)

Emmanuelle Riva, a French actress whose most memorable roles came more than 50 years apart, first in the 1959 classic “Hiroshima Mon Amour,” then in 2012’s “Amour,” for which she became the oldest person nominated for a best-actor Oscar, died Jan. 27 at a medical facility in Paris. She was 89.

Her agent, Anne Alvares Correa, confirmed the death to the Associated Press but did not specify a cause.

Ms. Riva was one of the most important film actresses in what became known as the French New Wave of the 1950s and 1960s, first gaining acclaim in director Alain Resnais’s “Hiroshima Mon Amour.” She played a French actress reflecting on an affair she had with a Japanese architect (Eiji Okada) in the aftermath of the destruction of the Hiroshima by an atomic bomb near the end of World War II.

It became a cinematic landmark and was praised as one of the most beautiful films ever made. A Time magazine critic in 1960 called it “an atomic horror movie, a pacifist tract, a Proustian exercise in recollection, a radioactive Romeo and Juliet.”

Much of its mesmerizing power came from Ms. Riva’s riveting performance. With a regal presence and large, expressive eyes, she recited lines from a poetically spare script by novelist Marguerite Duras, as she mused on love, war and memory.

French actress Emmanuelle Riva in 1970. (AFP/Getty Images)

Ms. Riva appeared in several other major films in the 1960s, including “Leon Morin, Priest” (1961), in which she played a wartime widow who falls in love with a priest, played by Jean-Paul Belmondo. The film was considered scandalous for its time.

In 1962, she had the title role in director Georges Franju’s “Therese,” playing an unhappy wife accused of poisoning her provincial husband.

Notoriously selective in her roles, Ms. Riva resisted popular fare and never made a film in Hollywood or in English. She continued to appear on stage in France and had occasional film roles, including one as Juliette Binoche’s mother in director Krzysztof Kieslowski’s acclaimed “Three Colors: Blue” in 1993.

Yet Ms. Riva she remained something of a film-buff secret until Austrian director Michael Haneke asked her to appear in “Amour.” She was 85 when the film was released in 2012.

“I immediately sensed that there was something extraordinary about the script,” Ms. Riva told the New York Times in 2013. “I sensed it intimately, without the least vanity. I knew I could do it, I wanted to do it right away, and I lived through it with passion.”

The French-language film is about an aging married couple, both of them music teachers, facing their inevitable decline. The husband is played by Jean-Louis Trintignant, who starred in “A Man and a Woman” in 1966.

Ms. Riva’s character has a stroke in the film and becomes increasingly incapacitated, sometimes humiliatingly so. Her husband feeds her by the spoonful, and when she spits her food in his face, he slaps her in exasperation.

French actress Emmanuelle Riva in 2013. (Patrick Kovarik/AFP/Getty Images)

Her performance was a display of remarkable subtlety, often without the use of words. She seemed to shrink in size throughout the film, as her eyes dimmed and her features lost their vitality.

“Amour” won the top prize at the Cannes Film Festival and received the Academy Award for best foreign film. Ms. Riva won acting honors around the world, including the French Cesar award, and in 2013 became the oldest nominee, male or female, for a best-actor Oscar. (She lost to Jennifer Lawrence in “Silver Linings Playbook.”)

During the two months in which “Amour” was filmed, Ms. Riva lived in her dressing room at a studio outside Paris. It was part of her immersive approach to acting.

“Abandon yourself and give yourself over,” she told the Los Angeles Times in 2012. “We don’t play act — it’s not a game. It’s life.”

Paulette Germaine Riva was born Feb. 24, 1927, in Chenimenil, France. Her father was a sign painter.

By age 6, Ms. Riva wanted to be an actress, but her working-class parents discouraged her aspirations and she became an apprentice to a seamstress. She appeared in regional plays before winning a scholarship to a Paris acting school when she was 26.

“I wanted to live another life and many lives at once,’’ she told the Times. “Acting makes you live plenty of lives.”

She never married and resided for decades in a fourth-floor Paris apartment without an elevator. She did not own a television.

In addition to acting in more than 50 films and dozens of plays, Ms. Riva wrote three volumes of poetry. In 2009, she published of a book of photographs she had taken while on location in Japan for “Hiroshima Mon Amour.”

After her late-career renaissance with “Amour,” Ms. Riva took on several other film roles, some of which have yet to be released.

“Cinema is the art of the instant,” she said in 2012. “It’s in the moment. We practice and practice to find that instant of total liberty. . . . Shhhh. . . . It’s hard!”