Richard Mellon Scaife, the Pittsburgh philanthropist and reclusive heir to the Mellon banking fortune, whose support for right-wing causes laid the foundations for America’s modern conservative movement and fueled the 1998 impeachment of President Bill Clinton, died on Friday. He was 82.

Mr. Scaife’s death was reported by the The Pittsburgh Tribune-Review, a newspaper he owned. No cause of death was given.

Decades before David and Charles Koch bankrolled right-wing causes, Mr. Scaife and Joseph Coors, the beer magnate, were the leading financiers of the conservative crusade of the 1970s and ’80s, seeking to reverse the liberal traditions of Franklin D. Roosevelt’s New Deal and Lyndon B. Johnson’s Great Society.

Mr. Scaife (pronounced Skayf) inherited roughly $500 million in 1965, and with more family bequests and income from trust funds and investments in oil, steel and real estate, nearly tripled his net worth over his lifetime. But unlike his forebears, who were primarily benefactors of museums, public art collections, education and medicine, he gave hundreds of millions to promote conservative political causes...