For a guy who probably didn’t live to see his 22nd birthday, never had a steady job, and spent most of his post-pubescent life on the run, Billy the Kid hasn’t done too badly.

In the 126 years since his death, he has never stopped inspiring works by our foremost litterateurs. This includes fiction from Larry McMurty’s “Anything For Billy” (1988) and N. Scott Momaday,’s “The Ancient Child” (1989), poetry from Michael Ondaatje’s book-length poem “The Collected Works of Billy The Kid” (1970) to drama in Michael McClure’s “The Beard” (1965), in which Billy mates with Jean Harlow in the afterlife. And Gore Vidal’s “The Death of Billy the Kid” was the basis for the Paul Newman film “The Left Handed Gun” (1958). Aaron Copland wrote a ballet about him, and he’s been the subject of more films than all the presidents of America combined, including “Billy the Kid Versus Dracula” (1966) and the French film, “Requiem Pour Billy the Kid,” released in January.

Perhaps no other figure in American lore has generated so much fiction and fancy from so little fact. Michael Wallis’s “Billy the Kid — The Endless Ride” (Norton, 288 pages, $25.95) pursues his life and legend as doggedly as Pat Garrett once chased the real Billy, and with drastically different results: Garrett ended up killing Billy while Mr. Wallis becomes the first biographer to bring him to life.

The actual facts of the life of Billy the Kid — aka William H. Bonney, aka Henry McCarty — are almost as sparse as those of Crazy Horse. Catherine Antrim, his mother, was described by one acquaintance as “a jolly Irish lady, full of life … fun and mischief.” She died of tuberculosis when Billy, or Henry, as most people seemed to know him, was 14, and as Mr. Wallis reminds us, “There was little time to be a child on the frontier in nineteenth-century America.” Billy eventually drifted to Lincoln County, New Mexico — at the time the largest county in any U.S. state or territory, with a homicide rate 47 times higher than the national average. There Billy got mixed up in Lincoln County’s political and economic disputes (which, with participants named Antrim, Murphy, Dolan, McSween, Brady, and Garrett, seems like a page out of an Irish mob war), avenged the killings of his pals, and was finally killed himself in 1881. Just about everything else concerning his life is in dispute.

Much more than previous Billy the Kid chroniclers, including Robert Utley and the British historian Frederick Nolan, Mr. Wallis, a veteran chronicler of the Wild West, has succeeded in filling in the background surrounding the enigmatic Billy. Period witnesses claim he “was a good boy, maybe a little … mischievous at times,” that he was of slight build but blessed with great energy and sharp reflexes, that he was courteous to ladies, and that “his eyes were full of fun” — clearly his mother’s Irish lad. He may or may not have recited a little poetry; if he didn’t, it says something about his power to inspire legend that some thought he did.

Gradually, through Mr. Wallis’s deft brush strokes, an image begins to take shape. Dime novels, he writes, particularly appealed to working class boys such as Billy and his brothers, who were “eager to read about the perils of frontier life. … The pulps featured brigands, renegades, and rogues and transformed them into heroic criminals, driven to their lawless ways by social injustice and the need to defy an oppressive and corrupt establishment.” It appears the soulful young Billy might well have been influenced by the pulp fiction of his time and, in turn, such literature may have colored his contemporaries’ impressions of him.

The frontier of the late 1870s was filled with “Kids” — the Apache Kid, the Texas Kid, Jimmy the Kid, even the Pockmarked Kid — but Billy stood out, though “he would not be referred as Billy the Kid in print until just seven months before he died.” Far from being the common outlaw of countless B movies, Billy’s crimes, except for a handful of misdemeanors such as cattle theft, were virtually all to seek revenge for the murders of his friends. Mr. Wallis finds little evidence for the psychotic killer image depicted in countless fantasies. Rather, the Kid became “a convenient target for the Santa Fe Ring and the Dolan Faction,” who murdered his friends — “… they deliberately used him as a target bad boy in order to divert the adverse public attention coming to them.” A rather startling fact is that “among the more than fifty individuals indicted for crimes in the Lincoln County War, only the Kid was ever convicted.”

That Billy the Kid, under any name, has survived in American cultural memory for so long can be attributed in no small part to his popularity with the Hispanic population of Lincoln County: “While the Anglo establishments … propagated the demonic Billy the Kid, many in the Hispanic community cheered him as their hero. To them, he was not a ruthless killer but he was their El Chivato, their little Billy, a champion of the poor and oppressed. He became both the ultimate underdog and a true social bandit.”

Every generation, it seems, resurrects Billy and recasts him in a new light (in the “Young Guns” movies in the early 1990s he was marketed to misunderstood teenagers). No matter how the story is told, though, “Billy the Kid lives on. No matter how Billy is recast, whether as frontier psychopath, Irish terrorist, delinquent with a six gun, or Huck Finn as avenging angel, Michael Wallis has given him enough material for a couple more go-arounds.

Mr. Barra reviews books for Salon.com and was a finalist for the National Book Critics 2006 Nona Balakian Citation for Exellence in Reviewing.