Stretching from "Aaron, Sam, Arizona pioneer" to "Zutacapan, Acomo pueblo chief," the three-volume Encyclopedia of Frontier Biography profiles approximately 4,500 frontier pioneers and Native Americans. Dan L. Thrapp's comprehensive work will interest scholars, researchers, and general readers curious about the figures who developed, defended, decorated, and devilized the American West.   All the famous ones are here: Volume I (A-F) includes Billy the Kid, Daniel Boone, Calamity Jane, George Custer, Buffalo Bill, Cochise, and John C. Fremont, among others. There are also entries for worthies less well known: Big Nose Kate, Nellie Cashman, Scott Cooley, to cite a few. Even Gary Cooper and other actors who portrayed westerners are sketched in. Thrapp's richly detailed biographies are continued in Volumes II (G-O) and III (P-Z).   Thrapp has included seventeenth- and eighteenth-century figures in both New France and New England, as well as the trans-Appalachian country, but the majority are nineteenth-century men and women who discovered, settled, fought for, or simply lived in the raw lands west of the Mississippi River.