John Bardeen
The principle of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925. John Bardeen, Walter Brattain and William Shockley invented the first working transistors at Bell Labs, the point-contact transistor in 1947. Shockley introduced the improved bipolar junction transistor in 1948, which entered production in the early 1950s and led to the first widespread use of transistors.