Killeen is a city in Bell County, Texas, The United States. The population was 86,911 at the 2000 census. As of 2009, Killeen had 119,510 people. In 2010 Killeen's population shot to 127,921. Then in 2011 the population shot up to 140,021. It is a "principal city" of the Killeen–Temple–Fort Hood Metropolitan Statistical Area.Killeen is directly adjacent to the main cantonment of Fort Hood, and as such its economy heavily depends on the post and the soldiers (and their families) stationed there.Killeen, Burnet and Lampasas counties are represented in the Texas House of Representatives by the semiretired veterinarian and rancher Jimmie Don Aycock, a Republican first elected on Nov. 7, 2006.