Horst Willhelm Jakob Rittel (14 July 1930 – 9 July 1990) was a design theorist and university professor. He is best known for coining the term wicked problem, but his influence on design theory and practice was much wider. His field of work is the science of design, or, as it also known, the area of design theories and methods (DTM), with the understanding that activities like planning, engineering, and policy making are included as particular forms of design.