TXU (formerly TU Electric) NYSE: TXU is an energy company headquartered in Energy Plaza in Dallas, Texas. Founded in 1882 as a power provider for the city of Dallas. In 1917, the company was called Dallas Power & Light.

The company merged with Texas Power and Light and Texas Electric Service Company, two other utilities serving the Dallas/Fort Worth Metroplex, to become TU Electric ("TU" meaning "Texas Utilities") in 1984 and following acquisitions of The Energy Group plc in the United Kingdom and a power generator in Australia, simply became TXU.

In 1996, TU Electric merged with the parent company of Lone Star Gas, allowing TXU to become the largest provider of electricity and natural gas in the state of Texas (TXU would later sell its natural gas properties in 2005 to another Dallas-based firm, Atmos Energy). In 2002, the state of Texas deregulated TXU's monopoly on electricity and TXU now competes against other energy companies like Reliant Energy, Direct Energy, Stream Energy, Gexa Energy and Cirro Energy.

TXU divested itself of its European holdings in late 2002 and its Australian holdings in 2004, and in 2005 sold its natural gas properties to Atmos Energy. TXU's former Australian assets were sold to Singapore Power and then split up, with Singapore Power retaining the Distribution Businesses (electricity and natural gas distribution networks) in the southern Australian state of Victoria, while divesting the Retail and Generation businesses to Hong-Kong-based CLP (China Light & Power), trading as TRUenergy. On May 18, 2004 TXU and Capgemini then entered a limited partnership to form Capgemini Energy Limited Partnership, a new company that will initially provide business process services and information technology solutions to TXU.