Jean Edward Smith, a political scientist and renowned biographer whose works helped restore luster to the tarnished reputations of underrated presidents, died on Sept. 1 at his home in Huntington, W.Va. He was 86. 

The cause was complications of Parkinson’s disease, his wife, Christine Smith, said. In a long academic career, Dr. Smith had taught at Marshall University in Huntington for 12 years.

Dr. Smith was, in the words of the commentator George F. Will, “today’s foremost biographer of formidable figures in American history.” 

His subjects ranged from the relatively obscure, like Lucius D. Clay, the American Army officer who oversaw occupied Germany after World War II, to the most historically consequential, like Franklin D. Roosevelt. Dr. Smith won the Francis Parkman Prizefor his book “FDR” (2008), a door-stopper that ran 858 pages. (“Altogether, an exemplary and highly readable work that ably explains why F.D.R. merits continued honor,” Kirkus Reviews said).

He was perhaps best known for biographies of Ulysses S. Grant and Dwight D. Eisenhower, presidents who at times received low approval ratings from historians, and of Chief Justice John Marshall, whose legacy had seemed to have been lost in the flood of attention paid to the nation’s founders.

Dr. Smith’s biography “Grant” (2001) was among those that helped rehabilitate the 18th president’s reputation as an effective chief executive, despite overseeing an administration rife with corruption. 

Dr. Smith showed that Grant’s poor reputation as president had been fostered in part by biased graduate students at Columbia University who wrote the first studies of Reconstruction.