Ivan Sutherland
Built Sketchpad in 1963 and, with it, interactive computer graphics and direct manipulation.
Ivan Sutherland is an American computer scientist often called the father of computer graphics. His 1963 MIT thesis, Sketchpad, let a user draw directly on a screen with a light pen, manipulate shapes by hand, and declare constraints the computer would then maintain — the first real demonstration of direct manipulation and interactive graphics.
Sketchpad anticipated computer-aided design, object-oriented thinking, and the graphical interface years before the hardware was ready for them. Sutherland went on to pioneer virtual reality and to mentor a generation of researchers at Utah. He is a landmark in the history of programming.