Born in Pennsylvania, Girty and his brothers were taken prisoners when still children by the Senecas and adopted by them. It would be seven years before Girty returned to his family, during which time he had come to prefer the Native American way of life. During the American Revolution, he first sided with the colonial revolutionaries, but later served with the Loyalists and thus was viewed by American frontiersmen as a renegade and turncoat.
On October 1, 1779, Girty and Alexander McKee with the aid of a large force of Native Americans attacked and killed American forces returning from a trip to New Orleans. The ambush occurred near Dayton, Kentucky, opposite Cincinnati. Only a handful of the Americans survived, among them Colonel John Campbell and Captain Robert Benham.
Girty was present during the torture and execution of Continental ArmyColonel William Crawford by Native American leader Captain Pipe. Two witnesses of this torture and execution survived and were later interviewed regarding these events. One suggested that Girty was a pitiless instigator. The other claimed that Girty pleaded with the Native Americans on Crawford's behalf until threatened with death himself. The former account was popularized and served to vilify Girty during and after his lifetime.
Girty is also credited with saving the lives of many American prisoners of the natives, often by buying their freedom at his own expense.
After the end of the war, Simon Girty settled in Canada. He retired to his farm near Fort Malden (present-day Amherstburg, Ontario) prior to the outbreak of the War of 1812. Girty's son was killed in that conflict, reportedly while trying to rescue a wounded British officer from the battlefield. Despite popular myths to the contrary, Simon Girty had no part in that war, except as a refugee when the British retreated from Fort Malden. Nor was he killed with Tecumseh at the Battle of the Thames, as was widely reported. Over sixty years old, he was increasingly infirm with arthritis and had failing eyesight. Girty returned to his farm after the war and died completely blind in 1818 in Canada.
Simon Girty served as one of the jury members in Stephen Vincent Benet's short story "The Devil and Daniel Webster" and in the 1941 movie of the same title. In that story, he is described as "the renegade, who saw white men burned at the stake and whooped with the Indians to see them burn". Benet uses Girty's popular image for the story's dramatic purposes; all members of the jury are called by Satan and are supposed to be the worst villains in American history.
Hugh Henry Brackenridge took and edited the detailed recollections of one of the survivors of Crawford's execution, which were published under the title Dr. Knight's Narrative, and had a considerable impact on the reputation of Simon Girty as a renegade. The most detailed research into this publication to date clearly calls into question the motives of Brackenridge in his published account. See the article by Parker B. Brown entitled The Historical Accuracy of the Captivity Narrative of Doctor John Knight, which appeared on pages 53–67 of The Western Pennsylvania Historical Magazine, vol. 70, no. 1 (January 1987). (ref. Allan W. Eckert, That Dark and Bloody River).
Simon Girty is featured in Julius de Gruyter's novel Drum Beats on the Sandusky, which is a fictional account of one of Crawford's young volunteer soldier's reprieve from Indian capture and subsequent adventures while under Girty's custody. "Against this colorful and historically accurate background, de Gruyter has fashioned a gripping novel of Indian fighting, ambush, miraculous escape and pursuit." (Published 1969, Carlton Press, Inc, New York, N.Y.)
The American novelist, Joseph Altsheler, makes Simon Girty a turncoat and villain in several of his "Young Trailer Series" of eight juvenile fiction books from 1907-1911.
Canadian playwright Ed Butts wrote a play entitled The Fame of Simon Girty.
Simon Girty, the outlaw. An historical romance, Jones, U. J. (Uriah James), Philadelphia: G. B. Zeiber, 1846 (fiction)