Entergy Corp. is an integrated energy company engaged primarily in electric power production and retail distribution operations in the Deep South of the United States. It is headquartered in the Central Business District of New Orleans, Louisiana.

Entergy traces its history to November 13, 1913, with the formation of Arkansas Power Company. Founder Harvey C. Couch used sawdust from a lumber company to bring electricity to rural Arkansas. In the 1920s, Couch set his sights on buying electric companies in other states. In 1923, he merged four independent companies in Mississippi into Mississippi Power and Light. Two years later, he formed Louisiana Power and Light to provide power to his Mississippi customers from northern Louisiana's natural gas fields.

Meanwhile, in 1922, Sidney Mitchel of Electric Bond and Share Company (EBASCO), a subsidiary of General Electric, had merged several competing electric utilities in New Orleans into New Orleans Public Service, an EBASCO subsidiary. Mitchel began turning his attention to other territories, and eventually began competing with Couch. The two men ultimately decided to merge their resources. In 1925, Electric Power and Light Corporation, an EBASCO subsidiary headquartered in New Orleans, was formed with Couch as its president. It was the parent company for Mississippi Power and Light, Louisiana Power and Light, New Orleans Public Service, and Arkansas Power and Light.

EBASCO was ordered dissolved in 1949 under the provisions of the Public Utility Holding Company Act. Mississippi Power and Light, Louisiana Power and Light, New Orleans Public Service and Arkansas Power and Light were deemed to be an integrated system, and were reorganized under the control of a new holding company, Middle South Utilities. It changed its name to Entergy in 1989, and merged/bought Gulf States Utilities, based in Beaumont, Texas, as of 12:00 midnight, January 1, 1994.

Since its inception, Entergy has been headquartered in New Orleans. That city had also been home to Entergy's various corporate predecessors since 1925. After Hurricane Katrina hit the city of New Orleans in August 2005, Entergy temporarily relocated the 1,500 employees and contractors who worked at the headquarters to other cities, including Clinton, Mississippi, Little Rock, Arkansas, and The Woodlands, Texas. In April 2006, the company began moving back into its New Orleans headquarters.

Paul Hinnenkamp was named Chief Operating Officer and senior vice president in November 2015. He replaced Mark Savoff, who announced his retirement a few months earlier.

Prior to the use of the current Entergy logo (Shown in the summary box at the upper right of this page), each subsidiary had its own distinctive logo. Upon the renaming of the company from Middle South Utilities System to Entergy, the present logo was adopted.

Louisiana Power and light Company, for example (today's Entergy Louisiana) used this logo (shown at right) extensively from about 1967 to 1989, on buildings equipment, and advertising:

Entergy's service territory includes the southeast corner of Louisiana and the cities of Lafayette and Baton Rouge, the eastern three-fourths of Arkansas and the western half of Mississippi. It also includes part of southeastern Texas, including the Beaumont-Port Arthur-Orange and Conroe-Woodlands-Kingwood areas.

A member of the Fortune 500, Entergy owns and operates power plants with approximately 30,000 megawatts of electric generating capacity, and it is the second-largest nuclear generator in the United States after Exelon Corporation. It had annual revenues of more than $11 billion in 2010 and approximately 15,000 employees.

Entergy's main operating segments consist of the U.S. utility segment and the non-utility nuclear segment. The U.S. utility segment provides retail electricity services to approximately 2.7 million customers in Arkansas, Louisiana, Mississippi, and Texas. The non-utility nuclear segment operates a total of nine nuclear power plants:

The company's nuclear division is headquartered in Jackson, Mississippi.

Entergy operates more than 41 plants using natural gas, nuclear, coal, oil and hydroelectric power with approximately 30,000 megawatts of electric generating capacity to serve its 2.7 million customers in the Gulf South. Its extensive transmission system carries approximately 23,000 megawatts of power across more than 15,500 miles (24,900 km) of interconnected lines within a 112,000-square-mile (290,000 km) area.

Entergy is the only U.S. utility to make the Dow Jones Sustainability Index (DJSI) nine years in a row. The DJSI is a listing of the companies whose overall environmental, social and economic sustainability performance scores were in the top 10 percent for their sector. Entergy was named in 2008 to Forbes list of America's Most Trustworthy Companies, a ranking based on corporate governance practices and accounting transparency.

On February 24, 2010, the Vermont Senate voted to prevent the Vermont Public Service Board from issuing the necessary certificate that would allow for the Vermont Yankee plant to have its license renewed for another 20 years. The vote will not affect current operation of the plant, and the issue could be revisited by the legislature in either a special session later in 2010 or in its next regular session in 2011.

Entergy-Texas operates as a wholly owned subsidiary. This was done to prepare the Texas side for de-regulation under Texas law but later Entergy notified the Texas PUC it would not be splitting the Texas side off as a de-regulated operation (to do so would cost billions). So the Texas side has remained connected to the rest of the Entergy network, though it has its own CEO and until 2012, was based where the former Gulf States Utilities was, in Beaumont, Texas. Entergy-Texas has moved to the rapidly developing area of The Woodlands, which is now larger population wise than the Beaumont area.