An electric chair is a device used to execute an individual by electrocution. When used, the condemned person is strapped to a specially built wooden chair and electrocuted through electrodes fastened on the head and leg. This execution method, conceived in 1881 by a Buffalo, New York dentist named Alfred P. Southwick, was developed throughout the 1880s as a supposed humane alternative to hanging, and first used in 1890. The electric chair has been used in the United States and, for several decades, in the Philippines. While death was originally theorized to result from damage to the brain, it was shown in 1899 that it primarily results from ventricular fibrillation and eventual cardiac arrest.

Although the electric chair has long been a symbol of the death penalty in the United States, its use is in decline due to the rise of lethal injection, which is widely believed to be a more humane method of execution. While some states still maintain electrocution as a legal method of execution, today it is only maintained as a secondary method that may be chosen over lethal injection at the request of the prisoner, except in Tennessee and South Carolina, where it may be used without input from the prisoner if the drugs for lethal injection are not available. As of 2021, electrocution is an optional form of execution in the states of Alabama and Florida, both of which allow the prisoner to choose lethal injection as an alternative method. In the state of Kentucky, the electric chair has been retired, except for those who were sentenced to death for an offense committed prior to March 31, 1998, and who choose electrocution; inmates who do not choose electrocution and inmates sentenced to death for crimes committed after that date are executed by lethal injection. Electrocution is also authorized in Kentucky in case lethal injection is found unconstitutional by a court. The electric chair is an alternate form of execution approved for potential use in Arkansas, Mississippi, and Oklahoma if other forms of execution are found unconstitutional in the state at the time of execution.

On February 8, 2008, the Nebraska Supreme Court ruled that execution by electric chair was a "cruel and unusual punishment" under the state's constitution. This brought executions by this method to an end in Nebraska, which had been the last remaining state to retain electrocution as its sole method of execution.