The son of a politically connected cotton broker, Mr. Perot followed a long tradition of buccaneering Texas entrepreneurs. Following an unhappy stint in the peacetime Navy of the 1950s, he became a top salesman at IBM and was such an exhaustive peddler of computer hardware that he once met an annual sales quota in less than three weeks.

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Mr. Perot went into business for himself in 1962 and made a fortune twice over, starting two software companies that each sold for billions of dollars. He received national attention for showering his largesse on efforts to aid or free U.S. hostages in conflict zones from Vietnam to Lebanon.

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Most memorably, Mr. Perot claimed to have deployed a commando team to rescue two of his employees from an Iranian prison around the time of the revolution in 1979. According to participants and U.S. officials, the two, who had been jailed during the shah’s regime, actually were freed when revolutionaries opened the capital’s prisons, but the episode nevertheless played a sizable role in mythologizing Mr. Perot. It formed the basis of Ken Follett’s 1983 novel “On Wings of Eagles” and a subsequent TV movie.

It was with this reputation as a cowboy — others considered him a loose cannon — that Mr. Perot stepped fully into the national spotlight to seek the White House.

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In 1992, running without party affiliation, Mr. Perot received 19.7 million votes, draining support from both major-party candidates and contributing to the victory of Democrat Bill Clinton over the incumbent president, Republican George H.W. Bush.

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Mr. Perot’s 19 percent share of the total was the most for an independent or third-party candidate since former president Theodore Roosevelt won 27 percent of the vote in 1912. That showing ensured “Mr. Perot’s place in American history,” said Bruce Buchanan, a University of Texas political scientist who has written widely on presidential politics.

His legacy was evidenced nearly two decades later when the tea party reignited anti-incumbent fervor, although it mimicked only his demand for smaller government. By contrast, Mr. Perot eschewed conventional wisdom, Buchanan pointed out, “promising pain” in the form of higher taxes while also vowing to cut federal spending and the deficit.

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Mr. Perot — who had a high-pitched twang, diminutive stature and buzz cut held over from his days at the U.S. Naval Academy — was the antithesis of a made-for-TV candidate. Yet he employed that medium brilliantly, calling on his vast resources to buy large chunks of airtime to explain his political beliefs.

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At times sounding more like a professor conducting a tutorial than a candidate for the nation’s highest office, he constructed a dizzying array of charts and graphs to illustrate what was wrong with the country, interspersing his lecture with corny jokes and folksy metaphors.

Cantankerous, suspicious and with a predilection for conspiracy theories, Mr. Perot gave voice to voters’ frustrations about wars, inflation and partisan politics. He offered himself as an ultrapatriotic “Mr. Fix It” who would “take out the trash and clean out the barn.”

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A tangle of contradictions, Mr. Perot didn’t easily adapt to campaigning or the scrutiny it brought. He became rich from federal contracts while denouncing the size of government. He criticized the influence of lobbyists “in alligator shoes” while lobbying and winning a tax break for himself from members of Congress to whom he had contributed. In 2011, Forbes magazine ranked Mr. Perot as the 99th-richest American, worth $3.4 billion.

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When friends initially urged him to seek the presidency, Mr. Perot conceded that he was “temperamentally unsuited” for politics. It was his adamant opposition to the Persian Gulf War — in which U.S.-led forces drove Saddam Hussein’s Iraqi troops out of Kuwait in 1991 — that eventually prompted him to challenge the incumbent president and the Democratic nominee.

He announced his unorthodox campaign to CNN talk-show host Larry King, on the condition that supporters get his name on the ballot in all 50 states, and promised a campaign in which “we’ll get both parties’ heads straight.” Within minutes, his Dallas phones were so jammed that no one could call out.

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Calling his grass-roots campaign United We Stand America, Mr. Perot attracted voters from all points on the political compass.

He capitalized on Bush’s failure to live up to his “read my lips” vow not to increase taxes. Speaking as a businessman, Mr. Perot said, “the chief financial officers of a publicly traded corporation would be sent to prison if it kept books like our government.”

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Mr. Perot warned about the increasing national debt and, in the most memorable of his many pet phrases, bemoaned passage of the North American Free Trade Agreement, predicting it would produce a “giant sucking sound” of American jobs flying to Mexico. He walked a tightrope on social issues. He supported abortion and gay rights (although he said he had never met a gay person) and sex education in schools (including distribution of condoms); opposed reintroducing prayer in schools; and was evasive on gun control. But he saw little role for a president on such issues, saying they mostly should be left to the states.

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By summer 1992, Mr. Perot was leading the polls with 39 percent, compared with 31 percent for Bush and 25 percent for Clinton.

Then, in mid-July, he abruptly dropped out, saying the Democratic Party had “revitalized itself” and that he feared a three-way race would place the outcome with the House of Representatives. Nonetheless, on Oct. 1, responding to a “summons” from volunteers, he got back in, saying neither Clinton nor Bush had addressed the issues.

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Mr. Perot’s on-again, off-again candidacy and talk of conspiracies enhanced lingering worries that he was a kook.

Among his unsubstantiated claims were that the Bush administration knew that American POWs had been left behind after the war in Vietnam and that his hunt for them had been impeded by drug-running CIA agents; that he had been targeted for assassination by North Vietnamese officials and the Black Panthers; that armed hit men had broken into his Dallas compound but were chased by a guard dog; and that Republicans had distributed doctored photos of his daughter intended to smear her reputation and ruin her wedding.

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As Republican political analyst and commentator William Kristol put it, Mr. Perot was “not an entirely sane individual.”

His eccentricities extended to his choice of a running mate, retired Navy vice admiral James B. Stockdale. A highly decorated Vietnam POW, Stockdale quickly proved to be a liability on the campaign trail, infamously beginning the vice-presidential debate by saying: “Who am I? Why am I here?”

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Ultimately, Mr. Perot carried no state. His best showing was in Maine, where he edged out Bush for second place.

Four years later Mr. Perot ran as the candidate of the Reform Party, an organization he largely created and funded. He chose not to finance this campaign, instead accepting $29.2 million in federal funds for which he qualified as a result of his previous showing. He tapped a mild-mannered Washington economist, Pat Choate, as his running mate.

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But by then, the magic was gone. Clinton won a second term, easily defeating Republican Bob Dole, with Mr. Perot receiving just over 8 million votes, or 8.4 percent, less than half his 1992 total.

Henry Ross Perot was born in Texarkana, Tex., on June 27, 1930. His talent surfaced early: He qualified as an Eagle Scout in 13 months, a task that typically took three to five years.

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At the Naval Academy, Mr. Perot was in the middle of his class academically, but he became a battalion commander and president of the graduating Class of 1953.

After serving two years in the peacetime Navy, Mr. Perot tried unsuccessfully to get out of the remainder of his four-year obligation. His main complaint was that promotions were based on seniority rather than merit.

In 1957, he took a sales job with IBM in Dallas. He quit when IBM ignored his ideas to not only sell computers but also to service them and develop software.

In 1962, he founded Electronic Data Systems, taking supportive co-workers with him. EDS’s first contract, with the food company Frito-Lay, called for a computer system to be installed in two years. Working frantic, 80-hour weeks, Mr. Perot and his IBM alums completed the job in eight weeks.

When EDS’s stock went public in 1968 at 118 times earnings, many employees became instant millionaires. Mr. Perot sold EDS to General Motors in 1984 for $2.5 billion in cash and stock, and he joined the GM board. But he resigned two years later in a dispute over management practices, ridiculing fellow board members as “pet rocks” for management.

Mr. Perot next formed Perot Systems, which became a leader in health-care information technology. It had contracts with hospitals, physicians, insurers and the federal Centers for Disease Control and Prevention. He sold Perot Systems, with 23,000 employees, in 2009 to a family friend, Michael Dell, for $3.9 billion.

In 1956, Mr. Perot married Margot Birmingham, whom he met when he was a midshipman and she was a student at Goucher College outside Baltimore. In addition to his wife, survivors include five children; a sister; and 19 grandchildren.

For a person of such wealth, Mr. Perot led a relatively moderate lifestyle. He made his children bring their own popcorn to the movies, bought his suits at Men’s Wearhouse and ate at Dickey’s Barbecue Pit in Dallas.

His extravagances were jewelry for his wife and boats for himself. In later years, he became a collector of Americana, cramming his office with Remington bronzes, Rockwell paintings, a Gilbert Stuart portrait of George Washington, and a copy of the Magna Carta that he sold for more than $20 million in 2007.