And, he told Newsweek magazine in 1989, "they're the very bottom of the pecking order among Indian tribes out here. They're the country bumpkins. And I've always identified with that."
Hillerman, who had been in declining health in recent years, died of pulmonary failure at Presbyterian Hospital in Albuquerque, said his daughter, Anne Hillerman.
Beginning with "The Blessing Way," published in 1970 and introducing Lt. Joe Leaphorn of the Navajo Tribal Police, Hillerman wrote 18 novels featuring Leaphorn and the younger officer Jim Chee and set in the sprawling Navajo region of New Mexico, Arizona and Utah.
The longtime Albuquerque resident, whose novels were known for their atmospheric blend of contemporary crime and traditional tribal beliefs and customs, remained something of a critically acclaimed cult favorite until his 1986 novel "Skinwalkers" propelled him onto bestseller lists and his mysteries, including "A Thief of Time," began selling millions of copies.
His legion of fans included Robert Redford, who acquired the film rights to Hillerman's mystery series and executive-produced "The Dark Wind," which was released in Britain in 1992, and others for PBS.
Hillerman, whose novels have been published in more than 30 languages, received the Grand Master Award from the Mystery Writers of America in 1991.
And, in 2005, he received the Los Angeles Times Book Prizes' Robert Kirsch Award for lifetime achievement for having "reinvented the mystery novel as a venue for the exploration and celebration of Native American history, culture and identity."
As a writer, Hillerman was known for what Newsweek magazine in 1989 referred to as his brilliant "evocation of nature and place -- particularly the desolation of the Southwest." And in "examining the pain of cultural clashes," the magazine noted, "he creates morality plays that are as subtly colored as their landscape."
"I want to write an entertaining book," Hillerman told Newsweek, "and I'd like people to see the strength and dignity of a culture I admire."
Otto Penzler, owner of Mysterious Bookshop in New York City and founder of Mysterious Press, said Monday that before Hillerman, "nobody had written about American Indians in any meaningful way, approaching them not only as sympathetic characters but as intelligent, cultured, wise and decent human beings the same way that people would look at people of any other race."
"He had a very colorful way of showing Indian culture, Navajo culture in particular."
Carolyn Marino, Hillerman's editor at HarperCollins, said setting was so strong in each of Hillerman's mystery novels "that it almost becomes a character."
"He also creates very vivid, very compassionate characters," she said. "These are mystery novels, and yet I think Tony transcended the mystery field. I think readers who may not read a lot of other mystery writers, read Tony."
In 1987, Hillerman received the "Special Friend of the Dineh" award -- dineh means "the people" in Navajo -- for his "accurate and sensitive portrayal of the strength and dignity of traditional Navajo culture."
"It's always troubled me that the American people are so ignorant of these rich Indian cultures," Hillerman once told Publishers Weekly. "I think it's important to show that aspects of ancient Indian ways are still very much alive and are highly germane even to our ways."
One of three children, Hillerman was born May 27, 1925, in the tiny farm town of Sacred Heart, Okla.
Hillerman, whose father was a farmer and general store operator, developed an early respect for Native American culture.