Rex W. Tillerson, the chief executive of Exxon Mobil and now President-elect Donald J. Trump's nominee for secretary of state, was probably the man least expected to show up at a town council meeting in North Texas to oppose a local construction project.

His complaint: A proposed water tower in Bartonville, Tex., meant to help use hydraulic fracturing to coax natural gas out of a shale field, would decrease the property value of his nearby ranch. He joined a suit to halt construction.

Mr. Tillerson dropped out of the suit after a judge threw out his complaint - and after news media reports implied he was hypocritically pursuing his backyard interests in opposing a project of a sort that Exxon Mobil has engaged in around the world. Admirers might cite Mr. Tillerson's willingness to change course as a sign of being nimble when necessary.

Depending on the circumstances, Mr. Tillerson has shown toughness or flexibility, whether in international negotiations, or on climate changepolicy and with gay rights - when he quietly lobbied for reform in the Boy Scouts.

As the leader of the biggest oil company in the United States, and with his close relations to President Vladimir V. Putin of Russia and a controversial record on climate change, Mr. Tillerson, 64, is likely to be a lightning rod for Democratic and some Republican senators as he seeks confirmation.

But executives at Exxon Mobil and around the oil business have said that Mr. Tillerson has learned to get along with Mr. Putin strictly for business reasons, but that he does not have a particular fondness for him. And supporters extol Mr. Tillerson's intelligence.

Detractors, though, view him as the epitome of an industry whose activities harm the environment and whose interests lie squarely with lifting sanctions on Russia.

If Mr. Tillerson is confirmed, the State Department would be the latest step up in a career and life with humble origins. He has a strong Texas twang as befits a man born in Wichita Falls, a North Texas town known mainly for its Air Force base and its tornadoes.

He grew up in a family of modest means; his father was an administrator for the Boy Scouts. Mr. Tillerson became an Eagle Scout at age 13; he later graduated with a degree in civil engineering from the University of Texas at Austin, where he played drums in the Longhorns' marching band.

Married and with four children, he is known as a an observant Christian and political conservative. He has said his favorite book is "Atlas Shrugged," a libertarian novel by Ayn Rand.

Those who know him say he has a Texas-size ego and can show flashes of anger when things do not go his way.

Throughout his professional life, Mr. Tillerson has been involved in charities. He was a national president of the Boy Scouts of America and is a former director of the United Negro College Fund.

He showed interest in foreign affairs when serving as a trustee for the Center of Strategic and International Studies. He was on that Washington think tank's board with Zbigniew K. Brzezinski, a former national security adviser, and Henry A. Kissinger, a former secretary of state, among others.

Under the leadership of Mr. Tillerson, who has been chairman and chief executive since 2006, Exxon Mobil shifted its approach to climate policy - although environmentalists may disagree. The company has acknowledged the science underlying climate change, and has stopped funding some groups that spread false data about global warming. The company also put support behind carbon taxes and last December's Paris climate agreement.

Having spent his entire career with Exxon Mobil and having been considered in some circles a leading spokesman of the oil industry, Mr. Tillerson is generally viewed as an unconventional choice for secretary of state. He has never held a diplomatic job nor a position in government. He rarely, if ever, speaks publicly on matters outside energy policy.

But he has extensive international business experience. He led the negotiations of an oil consortium seeking to build a gas export plant in Yemen, and oversaw increasing company involvement in Russia's oil and gas fields.

Mr. Tillerson has managed partnerships with Russian and Qatari state oil businesses, and supervised the activities of Exxon Mobil, which has operations in more than four dozen countries. In Iraq, the company has worked with the Baghdad government, but also with regional Kurdish leaders whose independence sometimes irks the Iraqi government.

From the very beginning of his leadership, he has faced international crises.

Shortly after he took over the company, President Hugo Chávez of Venezuela moved to nationalize the assets of more than 20 foreign oil companies. Exxon Mobil was one of two that resisted, and took Venezuela to international arbitration court. The company won a settlement of $1.6 billion, although that was a small fraction of what the company lost.

Bigger challenges awaited him in Russia. When Mr. Putin pressured Royal Dutch Shell to sell a major stake in its $20 billion Sakhalin Island oil and gas project to the state company Gazprom, Exxon Mobil avoided similar treatment. Executives said Mr. Tillerson dug in his heels and was a tough bargainer.

When the United States and its European allies sought to punish Russia in 2014 for its aggression in Ukraine, Mr. Tillerson found legal ways to work around initial sanctions. But when the sanctions were tightened, he froze many activities in the country.

Senator Marco Rubio of Florida, a Republican, has already cited Mr. Tillerson's ties to Russia as concerning. "The next secretary of state must be someone who views the world with moral clarity, is free of potential conflicts of interest, has a clear sense of America's interests and will be a forceful advocate for America's foreign policy goals," Mr. Rubio said.

But it may be on the issue of climate change that Mr. Tillerson has been viewed with the most skepticism.

Reporting by Inside Climate News and the Columbia University Graduate School of Journalism, published in The Los Angeles Times, has criticized Exxon Mobil for publicly questioning the scientific consensus on climate change even while its researchers were warning Exxon executives that the use of fossil fuels was a threat to the planet.

Mr. Tillerson has led the company in aggressively disputing those reports and in resisting investigations by state attorneys general, including Eric T. Schneiderman of New York, into allegations of a decades-long deception by Exxon Mobil.

The state inquiries include questions of whether the company is fraudulently misleading shareholders and consumers about climate change and the long-term prospects for fossil fuels, for example, in the way it assigns value to its oil and gas reserves.

Scientists have suggested that to avoid the worst effects of warming, companies like Exxon Mobil will not be able to extract a large portion of its oil and gas reserves. The federal Securities and Exchange Commission is also investigating Exxon Mobil's bookkeeping on reserves, and the company recently conceded it may have to write down some of those values, particularly in Canada, because of continuing low prices.