Raymond Reiter, Professor of computer science at the University of Toronto, a Fellow of the Royal Society of Canada, and winner of the 1993 - IJCAI Outstanding Research Scientist Award, died September 16, 2002, after a year-long struggle with cancer. Reiter, known throughout the world as ``Ray,'' made foundational contributions to artificial intelligence, knowledge representation and databases, and theorem proving. The memoriam describes Professor Reiter and his foundational contributions to artificial intelligence.