Mikhail Kalashnikov, the former Red Army sergeant behind one of the world’s most omnipresent weapons — the AK-47 and its variants and copies, used by national armies, terrorists, drug gangs, bank robbers, revolutionaries and jihadists — died Dec. 23 at a hospital in Izhevsk, Russia. He was 94.

He lived in Izhevsk, the capital of the Russian republic of Udmurtia. Viktor Chulkov, a spokesman for the republic’s president, confirmed the death to news sources but did not give a cause. Mr. Kalashnikov had been hospitalized for the past month with unspecified health problems.

Mr. Kalashnikov began life as a sickly child in a peasant family and would have seemed an unlikely candidate for the international fame he achieved. He became a folk hero in his native land and a celebrity abroad. Despite having little technical training, he rose to the top of the Soviet armaments industry and traveled throughout the world, including the United States, as the face of Russian weaponry, an advertisement for a Soviet product that actually worked.

Jim Supica, director of the National Firearms Museum in Fairfax County, called Mr. Kalashnikov a “giant of firearms design. Kalashnikov’s genius was in designing a military rifle that was cheap to manufacture, rugged and reliable.”

Mr. Kalashnikov headed the design team that produced the AK-47 — standing for automatic by Kalashnikov, model of 1947 — as the assault rifle for the newly retitled Soviet Army. It went into service two years later and then was provided to the Soviet Union’s allies and clients, as well as many other countries Moscow was trying to influence during the Cold War and after.

A totemic weapon

The AK first went into action to put down East Berlin riots in 1953 and the Hungarian Revolution of 1956. Egyptian soldiers used it to assassinate President Anwar Sadat in 1981. Troops on both sides in the Iran-Iraq war carried it. The al-Qaeda leader Osama bin Laden used a modernized one as a prop in his recruiting videos.

From its earliest days, the Kalashnikov has been judged a superior weapon because of its simplicity and reliability. In a compact, 10-pound package, a single fighter holds the fully automatic firepower of a machine gun. It has only eight moving parts, can be broken down and reassembled in 30 seconds and will fire when very dirty.

During the war in Vietnam, the rifle was used by the North Vietnamese army, Viet Cong insurgents and, sometimes, U.S. forces. Marines would often put down their standard-issue M-16s and pick up AK-47s from fallen North Vietnamese soldiers because they found the AK to be more reliable.

Over the years, two dozen nations have produced the rifle, including Warsaw Pact members, China, North Korea, Egypt, Iraq and Finland. Before his death in 2013, President Hugo Chavez of Venezuela was planning to open a factory to manufacture the gun, and the AK is wielded in battle today by al-Qaeda in Iraq, the Taliban in Afghanistan and anti-government rebels in Syria.

No exact count is possible, but experts think there are about 100 million AKs, modernizations and derivatives around the world, with as many as 1 million more being made each year.

In the United States, the AK and all other fully automatic weapons are illegal for most civilians. As a weapon designed for military use, an authentic AK can be switched between automatic and single-shot modes with the flip of a lever. The assault rifles for sale in the United States are semiautomatic — that is, one shot per trigger-pull. Those seen blazing away in Hollywood movies are disabled weapons that can fire only blanks.

The AK brand did succeed in invading the United States, but through popular culture, where it symbolizes a kind of rebellious cool. Sylvester Stallone carried one in the “Rambo” movies, as did Nicolas Cage, Warren Beatty and hundreds of actors in other films. Rapper Lil Wayne scored a hit with his song “AK-47,” and Tupac Shakur had an image of the gun tattooed on his stomach. Many video games, such as “Grand Theft Auto,” feature AKs.

At a ceremony marking the 60th anniversary of the rifle, Mr. Kalashnikov paid tribute to the team that helped him create the AK. “I was not by myself, sitting at a desk,” he said. “It was a thousand-strong collective working at different factories.”

But the weapon bears his name.

A sergeant’s gift for design

Mikhail Timofeyevich Kalashnikov was born Nov. 10, 1919, in Kurya, a village in south-central Russia. He was the eighth of 18 children, only eight of whom survived to adulthood.

When Joseph Stalin launched his campaign to collectivize farms into government-operated units, the Kalashnikovs were viewed as obstacles to the plan. They were labeled kulaks, or rich peasants, and exiled in 1930 to Tomsk Oblast in Siberia.

Mikhail Kalashnikov’s father died a year later, and Mikhail’s mother soon married a widower with three children of his own. At 16, Mikhail Kalashnikov left his unguarded home in exile and fled to neighboring Kazakhstan, where he got a job in a rail yard of the Turkestan-Siberian Railway.

By 1938, when he was drafted into the Red Army, as it was then called, his skill with tools helped earn him an assignment to an armored unit that later was equipped with the new T-34 tank. Tinkering in earnest now, he invented devices to count the hours a tank’s engines were running and the number of bullets fired by its machine guns.

Mr. Kalashnikov told his life story in memoirs, articles and interviews, some contradicting others, and there were almost as many variants in his recollections as his famous assault rifle generated. In his definitive book, “ The Gun ,” biographer C. J. Chivers sorted through the stories and offered the most reliable narrative available in the West.

During a 1941 battle with German forces at Bryansk in western Russia, then-Sgt. Kalashnikov was wounded in either the chest or the shoulder.

While recovering at a hospital in Yelets, south of Moscow, he said, he listened to heated discussions among fellow soldiers about the excellent weapons the Germans fielded and the shortcomings of the Russian counterparts. They were particularly unhappy with their rifles, which were often retreads of single-shot weapons dating back to Czarist arsenals.

On medical leave for six months, Mr. Kalashnikov returned to Kazakhstan and his railroad office. He enlisted his workmates in designing and making a prototype of a new submachine gun, which he presented to a senior official for evaluation.

The gun was dismissed as no improvement on one already in the Soviet arsenal, but its designer was given a new assignment. He was sent to work in a series of military firearms labs, often in secret cities closed to outsiders.

At first, Mr. Kalashnikov and his team of gunsmiths and engineers focused on a gas-operated, semiautomatic carbine, adapting technology used in the U.S. Army’s M-1 Garand rifle and an earlier Soviet version, but their design lost out to one from a rival weapons lab.

Using the same principle — rechanneling the expanding gases from one shot to reload the firing chamber with another cartridge — the Soviet team developed the AK-47, which won the national competition for an automatic rifle.

Soviet hero

The Soviet Union’s propagandists were always looking for proletarian heroes to serve as role models, and they found one in the peasant weapons designer and former tank corps sergeant.

Mr. Kalashnikov, who attained the reserve rank of lieutenant general, was showered with awards, titles, bonuses and favors. He was awarded the USSR State Prize and the Stalin Prize in 1949. Later came Hero of Socialist Labor (twice), the Lenin Prize (twice) and many others.

After the breakup of the Soviet Union, Mr. Kalashnikov continued to work at the armaments plant in Izhevsk, Russia. As an employee of the state, he earned no royalties but did receive special access to autos and a country cottage. He franchised his name to makers of vodka, umbrellas, pocket knives and other novelties, but sales were slow.

His wife, the former Ekaterina Viktorovna, who also worked in the weapons plant at Izhevsk, died in 1977. Survivors include three children. A complete list of survivors could not be confirmed.

Chivers, who interviewed Mr. Kalashnikov several times, noted that one of the keys to the designer’s success was his natural charm and cooperative attitude. He was helped along by Communist Party ties. He joined the Komsomol, the young communist league, at the railway yard in Kazakhstan and went on to full party membership. Years later he was made a member of the Supreme Soviet, Moscow’s purely ceremonial parliament.

He formed friendships with senior Soviet generals and officials and with his fellow weapons workers, who seemed fond of him. He did confide that he concealed his kulak background for many years. “I was haunted by the fear that someone might find out about my past as a deportee,” he said.

Interviewers regularly asked him what he thought of the damage and suffering his weapons had caused. He usually answered with some variation of what he said in the Kremlin after a celebration of his 90th birthday in 2009.

“I sleep soundly,” he said. “I created a weapon to defend the motherland. It was not my fault that it was sometimes used where it should not have been. That is the fault of politicians.”