Allegheny Energy is an electric utility headquartered in Greensburg, Pennsylvania. It owns and operates electric generation facilities and delivers electric services to customers in Pennsylvania, West Virginia, Maryland, and Virginia. Allegheny Energy was incorporated in Maryland in 1925. However, some of its predecessor companies have been serving their communities for over a century.

The company has three primary businesses: merchant generation, which operates power plants primarily in Pennsylvania and West Virginia; transmission expansion; and utility operations, consisting of transmission and distribution operations serving 1.6 million customers, primarily in small towns and rural areas.

Southwestern Pennsylvania, excluding the city of Pittsburgh, provides about half of regulated utility revenues.

Allegheny Energy operates its electric distribution operations under the trade name Allegheny Power. Its regulated subsidiaries are West Penn Power (Pennsylvania), Monongahela Power (northern West Virginia), and The Potomac Edison Company (western Maryland, parts of eastern West Virginia, and northern Virginia). The electric generating plants are operated by subsidiary Allegheny Energy Supply Company and Monongahela Power. Subsidiary companies have been established for proposed transmission line projects.