American psychologist, and advocate of Programmed Instruction. Inventor of Skinner's Teaching Machine and Project Pigeon
B.F. Skinner at the Harvard Psychology Department, circa 1950 - wikipedia 
Skinner did not invent Behaviorism but was the inventor and chief proponent of Radical Behaviorism, a form of it.
Skinner's primary contribution to Behaviorism seems to be in the level of abstraction he brought to the field, which allowed it to operate as an experimental domain in which studies of discrete phenomena could build off one another.
He argued, for example, that "a stimulus or a response is a class, not a unique event. A stimulus or response should be defined by what it does, rather than how it looks." html 
Conceptually, he was also responsible for the idea of Stimulus Control, the recognition that stimulus and response do not have to exist in a one-to-one ratio.