Lee de Forest (August 26, 1873 – June 30, 1961) was an American inventor, electrical engineer, and early pioneer in electronics of fundamental importance. He invented the first practical electronic amplifier,
the three-element "Audion" triode vacuum tube in 1908. This helped start the Electronic Age, and enabled the development of the electronic oscillator. These made radio broadcasting and long-distance telephone lines possible, and led to the development of talking motion pictures, among countless other applications.
He had over 300 patents worldwide, but also a tumultuous career – he boasted that he made, then lost, four fortunes.