Gregor Kiczales is an American computer scientist. He is currently a full time professor of computer science at the University of British Columbia in Vancouver, British Columbia, Canada. He is best known for developing the concept of aspect-oriented programming, and the AspectJ extension to the Java programming language, both of which he designed while working at Xerox PARC. He is also one of the co-authors of the specification for the Common Lisp Object System, and is the author of the book The Art of the Metaobject Protocol, along with and Daniel G. Bobrow.