Pagan Kennedy at the NYTimes tells us who made the Escape Key:

The key was born in 1960, when an I.B.M. programmer named Bob Bemer was trying to solve a Tower of Babel problem: computers from different manufacturers communicated in a variety of codes. Bemer invented the ESC key as way for programmers to switch from one kind of code to another. Later on, when computer codes were standardized (an effort in which Bemer played a leading role), ESC became a kind of "interrupt" button on the PC -- a way to poke the computer and say, "Cut it out."

As antiquated as some people might consider it today, I still use it a lot.