big iron
A country ballad by Marty Robbins, from his 1959 album Gunfighter Ballads and Trail Songs. "Big Iron" tells the story of an unnamed Arizona Ranger who rides into the town of Agua Fria sometime between 1901 and 1909 (the years of the original Ranger organization's existence). Unnerved by his silence and the large handgun he carries (the eponymous "big iron"), the townsfolk initially take the Ranger for an outlaw, until he explains that he is hunting a notorious outlaw called Texas Red.
Long overshadowed in Robbins's canon by "El Paso" from the same album, "Big Iron" entered 21st-century meme culture through its appearance on the soundtrack of Fallout: New Vegas in 2010.