Alan Kay coined the term object oriented programming in the 60's. Even though the progression of this paradigm has been a collaborative effort, Alan Kay has played a very important part in the creation of this paradigm.
In 2003 Stephan Ram could not find an authoritative source on what "object oriented" really meant, so he decided to ask Alan Kay himself.
Here's a link to his reply. A must read for anyone who is interested in object oriented programming and design.