Julia Kathryn Garrett, teacher and author, daughter of Sam and Lilli Garrett, was born on October 15, 1897, in Fort Worth, Texas. Her father worked as a railroad conductor for the Texas and Pacific Railway. After attending high school in Fort Worth, Kathryn Garrett graduated with a B.A. in history from Randolph-Macon Women's College. She received an M.A. (1924) and a Ph.D. (1934) from the University of California at Berkeley. She also briefly attended Oxford University. She began her teaching career at Eleventh Ward School in Fort Worth. After a year she moved to Ranger, where she taught for a year and a half before returning to Fort Worth. In her forty-five years in Fort Worth, she taught at several schools, including Jennings Avenue Junior High, Parker Junior High, Central High School (later Paschal High School), and Arlington Heights High School. From 1945 until her retirement in 1966 she spent the bulk of her time at Arlington Heights, where she served as chairman of the history department and sponsor of the Junior Historians of Texas.
She was the author of Green Flag over Texas: A Story of the Last Years of Spain in Texas (1939) and Fort Worth: A Frontier Triumph (1972), the latter the result of a lifetime of research, which traces Fort Worth history from the sixteenth century through Reconstruction in a graceful prose style that helps make the book a definitive work on the subject. She coauthored Down Historic Trails of Fort Worth and Tarrant County (1949), A History of Texas: Land of Promise (1949), and Our American Constitution: The Story of a Great Document (1966). Garrett also published several articles in the Southwestern Historical Quarterly, in which she identified the first newspaper of Texas, the Gaceta de Texas; argued that the first constitution of Texas was written on April 17, 1813; and presented research based on the private papers of Dr. John Sibley.
She received a certificate of commendation from the Texas Historical Commission and a certificate of recognition from the Tarrant County Historical Society. She was a fellow of the Texas State Historical Association and received its Leadership Award in 1980. She was a member of the Texas State Historical Association, the Tarrant County Historical Society, the National Education Association, the Fort Worth Retired Teachers Association, the National Retired Teachers Association, Delta Kappa Gamma, Sigma Kappa Alpha, the Women's Club of Fort Worth, and the First Presbyterian Church. The city of Fort Worth celebrated Julia Kathryn Garrett Day in 1979. Julia Garrett never married. She died at the age of ninety-one on November 20, 1988, and was buried at Greenwood Memorial Park, Fort Worth.