Lost Creek is an affluent upper-middle-class neighborhood and census-designated place (CDP) of approximately 4,500 people in Travis County, Texas, United States. The census tract is bordered by Capital of Texas Highway to the east, Barton Creek to the south, Barton Creek Boulevard to the west, and Bee Caves Road to the north. The Lost Creek CDP encompasses several small neighborhoods—Parkstone, Woods of Westlake, Camelot, and Knollwood—as well as the largest and most populous Lost Creek neighborhood. The United States Census Bureau reports a total area of 3.1 square miles (8.1 km²), all of it land.
Suburban residential development began in the late 1970s and continued for over three decades. Lost Creek is almost completely built-out. Lost Creek also encompasses a commercial area bordering Bee Caves Road and Capital of Texas Highway. Businesses occupying these buildings include Capital One Bank, Wells Fargo Bank, and Apple Inc.