The Texas Ranger Division, commonly called the Texas Rangers and also known as "Los Diablos Tejanos"—"the Texan Devils", is an investigative law enforcement agency with statewide jurisdiction in Texas, based in the capital city of Austin. Over the years, the Texas Rangers have investigated crimes ranging from murder to political corruption, acted in riot control and as detectives, protected the governor of Texas, tracked down fugitives, and functioned as a paramilitary force at the service of both the Republic (1836–1845) and the state of Texas.

The Texas Rangers were unofficially created by Stephen F. Austin in a call-to-arms written in 1823 and were first headed by Captain Morris. After a decade, on August 10, 1835, Daniel Parker introduced a resolution to the Permanent Council creating a body of rangers to protect the Mexican border. The unit was dissolved by the federal authorities during the post–Civil War Reconstruction Era, but was quickly reformed upon the reinstitution of home government. Since 1935, the organization has been a division of the Texas Department of Public Safety (TxDPS); it fulfills the role of Texas' state bureau of investigation. As of 2019, there are 166 commissioned members of the Ranger force.The Rangers have taken part in many of the most important events of Texas history, such as stopping the assassination of presidents William Howard Taft and Porfirio Díaz in El Paso, and in some of the best-known criminal cases in the history of the Old West, such as those of gunfighter John Wesley Hardin, bank robber Sam Bass, and outlaws Bonnie and Clyde. Scores of books have been written about the Rangers, from well-researched works of nonfiction to pulp novels and other such fiction, making the Rangers significant participants in the mythology of the Wild West. The Lone Ranger, perhaps the best-known example of a fictional character derived from the Texas Rangers, draws his alias from having once been a Texas Ranger. Other well-known examples include the radio and television series Tales of the Texas Rangers, and the several Texas Ranger roles, including Chuck Norris portraying Cordell Walker in Walker, Texas Ranger.

The Rangers are culturally significant to Texans and are legally protected against disbandment. There is a museum dedicated to the Texas Rangers known as the Texas Ranger Hall of Fame and Museum in Waco, Texas, which celebrates the cultural significance of the Rangers.