Larry Gibson, an unlikely activist who fought West Virginia’s powerful coal interests to preserve a mountain that had been his family’s home for generations, died Sept. 9 at a hospital in Charleston, W.Va. He had a heart attack while working at his family’s property on Kayford Mountain in Raleigh County, W.Va., his daughter, Victoria Gibson, said. He was 66.

Mr. Gibson was best known for his tireless and often courageous opposition to a mining practice called mountaintop removal. After being away from West Virginia for many years, he returned to Kayford Mountain in 1986 and discovered a landscape that was beginning to change beyond recognition.

Where there had once been verdant mountain ridges, Mr. Gibson now saw desolate ­stretches of land where mining companies had dynamited the mountaintops to expose seams of coal within. Trees and rocks had been bulldozed into valleys and streams below.

“Growing up here was an adventure every day,” he said in an online video made for Earth­justice, a nonprofit legal organization formerly known as the Sierra Club Legal Defense Fund. “I played with my pet bobcat, my fox, my hawk.”

By the 1990s, his family’s 54 acres were the only patch of green remaining near Kayford Mountain.

Larry Gibson, an unlikely activist who fought West Virginia’s powerful coal interests to preserve a mountain that had been his family’s home for generations, died Sept. 9 at a hospital in Charleston, W.Va. (Frank Johnston/The Washington Post)

“Just a stone’s throw away, on that mountaintop removal mining site,” he said, “you couldn’t find anything alive if you wanted to. It’s bare rock, uninhabitable.”

Mr. Gibson’s father and grandfather had been coal miners, and he often said that he had no objections to mining that left the mountains intact. What made him angry was to see the wholesale defacement of the landscape, wildlife and the mountain culture for which West Virginia is known.

“God created these mountains,” he told The Washington Post in 1998. “Only God should be able to take them away.”

Mr. Gibson stood only 5-feet-2, but he often stood up against his state’s most powerful private interests in his effort to stop mountaintop removal or, as the mining companies sometimes call it, peak reduction.

It was not a popular stance to take in West Virginia.

He was often arrested — including once at the governor’s office — and was continually under surveillance by private security teams in pickup trucks. He was forced off mountain roads and sometimes found bullet holes in his property.

“I’d like to get along with the coal companies,” Mr. Gibson told the Charleston Gazette in 1997. “But I don’t have to just sit back and let them do whatever they want.”

He established the Keeper of the Mountains Foundation, testified before the United Nations and spoke about mountaintop removal at colleges throughout the country, including Virginia Tech and Yale.

He showed up at shareholders’ meetings of large banks, protesting their investment in companies that practiced mountaintop removal. In 1999, he walked 500 miles across West Virginia to promote his cause. Six years later, Mr. Gibson led a march to the front door of the Richmond headquarters of Massey Energy — the same company that owned the Upper Big Branch Mine, in which 29 miners were killed in 2010.

“I’ve never met a braver man,” said Rob Perks, who formerly ran a campaign against mountaintop removal at the Natural Resources Defense Council. “He’s the one most responsible for getting ingrained in people’s minds what mountaintop removal is all about. He’s like Gandhi for this movement, he really is.”

Mr. Gibson was often confronted by miners and others who said he was trying to kill West Virginia’s leading industry, and some members of his own family disagreed with his tactics. And it would be an exaggeration to say his mission was a total success.

In spite of some increased oversight by the Environmental Protection Agency, mountaintop removal is still practiced in many parts of West Virginia, Virginia, Kentucky and Tennessee. After the coal is extracted, the mountains are sometimes replanted with trees or grass. Environmental advocates say that more than 500 mountains have been flattened by mountaintop removal, and more than 2,000 miles of streams have been buried in rubble.

Mr. Gibson said he turned down offers worth millions of dollars for his family’s ancestral land on Kayford. Instead, he set up a trust to preserve the property, including a family cemetery with gravestones dating to the 18th century.

“Why not let it go?” he said to a Virginia Tech class in 2004. “Because in that cemetery up there are buried members of my family as far back as the 1700s.”

Larry Lee Gibson was born March 5, 1946, in Kayford, W.Va. He was 7 when an older brother was struck and killed by a speeding drunk driver.

In 1957, his family moved to Cleveland, but young Mr. Gibson left school to find work when he was 13. He worked in auto factories in Ohio before taking early retirement after being injured in an industrial accident. He was 40 when he came back to West Virginia.

His first two marriages, to the former Carol Spangler and the former Sheila Crow, ended in divorce.

Survivors include his wife of four years, Carol Kirkpatrick Gibson of Charleston; two sons from his first marriage, Cameron Gibson of Jacksonville, Fla., and Larry Gibson Jr. of Charleston; a daughter from his second marriage, Victoria Gibson of Charleston; one sister; one brother; and five grandchildren.

For the past four years, Mr. Gibson divided his time between Charleston and Kayford Mountain. He was awkward when he first began to speak in public in the 1980s, but he soon became a powerful voice and was known to environmental advocates throughout the country.

“He’s so grounded in what is right,” said Janet Keating, executive director of the Ohio Valley Environmental Coalition in Huntington, W.Va. “He’s such a compelling speaker. He’s authentic, he’s real.”

Victoria Gibson said her father was working on Kayford Mountain the day he died.

In the hospital, she said, “You could smell the freshness of that air that was still on him. The dirt was embedded in his fingernails. It was traced through every finger, every knuckle and every crease.”