The transistor.
VisiCalc, released in 1979.
Today's computer would be nothing like it is now without the microprocessor. Most every electronic device has a microprocessor in it, from garage door openers, to remote controls, and cell phones. The microprocessor revolutionized electronics, giving them intelligence, and making our lives easier. Thus, it revolutionized the computer industry.
Henry Ford
sewing machine
Algol
Elias Howe
Pong, definitely
the invention of the cotton gin
the factory system
John Deere
Sameul Slater
Jeff Bezos