Martyl Langsdorf, an artist who designed one of the most enduring visual images of the 20th century, the Doomsday Clock, with its hands ticking toward midnight as a symbol of impending nuclear destruction, died March 26 at a rehabilitation facility in Schaumburg, Ill. She was 96.

She had complications from a lung infection, her daughter Suzanne Langsdorf said.

Mrs. Langsdorf was already a successful artist by the time she was asked to design the cover of the June 1947 issue of the Bulletin of the Atomic Scientists. Against an orange background, she set a quarter of a clock face, with a black hour hand pointing to the “12” position as a white minute hand approached 11:53.

Even without the accompanying articles about the danger of nuclear weapons, the implication was clear: The fate of the world was in doubt unless an escalating arms race could be stopped before it reached the doomsday hour of midnight.

“It’s such an intuitively tension-building image,” graphic designer Michael Bierut, who updated Mrs. Langsdorf’s design in 2007 and is on the board of the Bulletin of the Atomic Scientists, said Saturday in an interview. “To be able to reduce something that complex to something so simple and memorable is really a feat of magic.”

Martyl Langsdorf, seen here in 2006, created the Doomsday Clock image for a cover of the Bulletin of the Atomic Scientists. The clock became an iconic image of the nuclear threat. (BULLETIN OF THE ATOMIC SCIENTISTS)

It was the first and last magazine cover that Mrs. Langsdorf designed.

Two years later, in 1949, the Soviet Union tested its first nuclear weapon, and the Cold War began in earnest. The scientists who guided the bulletin — including Mrs. Langsdorf’s husband, nuclear physicist Alexander Langsdorf Jr. — reconfigured the image of the Doomsday Clock by moving its hands four minutes closer to midnight.

In one stroke, Mrs. Langsdorf’s design had been reinvented as a wide-reaching symbol of the age. A powerful idea was expressed in a visual image containing four dots and two lines.

“The scientists decided to use it imaginatively as a metaphor,” Bierut said. “That’s really a complex thing. “To wed this almost childish cliche to this fear of the annihilation of the Earth, that’s really remarkable.”

During World War II, Alexander Langsdorf had helped develop the atomic bomb as a member of the Manhattan Project. After bombs were dropped on Hiroshima and Nagasaki in Japan, leading to the end of the war, he began to have misgivings. He was one of about 70 scientists who signed a letter to President Harry S. Truman, pointing out the “solemn responsibility” of the United States to control the use of nuclear arms.

Mrs. Langsdorf’s simple visual image entered pop iconography as an element in songs by the Who, Iron Maiden and Bright Eyes. It was featured in novels and nonfiction books and became a near-universal symbol of the dangers lurking in the modern world.

In 2007, Mrs. Langsdorf recalled a visit to Japan with her husband in the 1970s.

Mrs. Langsdorf was already a successful artist when she designed the cover. “To be able to reduce something that complex to something so simple and memorable is really a feat of magic,” graphic designer Michael Bierut said. (BULLETIN OF THE ATOMIC SCIENTISTS)

“We were on a train that stopped in Hiroshima and everybody gets off to look at the monument,” she told the Chicago Sun-Times. “He didn’t get off the train. He refused to. And he had tears in his eyes, he was so upset at that whole thing.”

Martyl Suzanne Schweig was born March 16, 1917, in St. Louis. Her mother was an acclaimed artist, and her father was a photographer.

She studied piano and violin before focusing on painting at age 11. As a teenager, she had a private showing and sold a painting to composer George Gershwin, who was visiting St. Louis.

As a student at Washington University in St. Louis, she once finished second in a playwriting contest. Third place went to a fellow student named Thomas L. Williams, who became better known as Tennessee Williams.

Mrs. Langsdorf, who signed her work “Martyl” (pronounced mar-TILL), was also an artist with the Works Progress Administration, a Depression-era program that, among other things, employed artists to paint murals in public buildings. In the early 1940s, she painted a mural highlighting African American history at the Recorder of Deeds Building in Washington.

She and her husband were married in 1941 and moved to Chicago in 1943. They had lived since 1953 in a landmark house in Schaumburg, designed by architect Paul Schweikher.

Alexander Langsdorf spent most of his career at the Argonne National Laboratory before his death in 1996. Survivors include two daughters, Suzanne Langsdorf of Arlington County and Alexandra Shoemaker of Aptos, Calif.; a brother; four grandchildren; and two great-grandchildren.

Mrs. Langsdorf was resigned to being known as the “clock lady,” but she liked to point out that she had an 80-year career as a painter and printmaker. Her art was included in exhibitions at the Art Institute of Chicago, the Los Angeles County Museum of Art, the St. Louis Art Museum and other prestigious venues.

Her work, which consists largely of landscapes and still lifes, is in the permanent collections of many museums, including the Smithsonian American Art Museum and Hirshhorn Museum and Sculpture Garden in Washington. At the time of her death, she was preparing for a new gallery exhibition in Chicago.

Since 1947, Mrs. Langsdorf’s Doomsday Clock reappeared often on the cover of the Bulletin of the Atomic Scientists, reflecting the changing state of the world.

From 1991 to 1995, during an era of arms reductions, the hands were pushed back to 11:43. The closest the clock has ever come to midnight was in 1953, when it reached 11:58 after the United States tested its first hydrogen bomb. A panel of scientists now meets each year to set the time of the Doomsday Clock, reflecting newfound worries about climate change and bioterrorism, as well as nuclear arsenals. When the panel released its most recent assessment in January, it concluded that, in doomsday time, it is five minutes to midnight.