Stefan Diez (born 1971 in Freising) is a German designer and studio owner, who studied Industrial Design at the State Academy of Art and Design Stuttgart. He owns a design studio, and develops furniture, tableware, bags, accessories, and exhibition designs.

Stefan Diez's introduction to furniture design started in 1991 when, for three years, he worked as a cabinet maker. Having spent a year working in Mumbai and Poona, India, Diez returned to Germany in 1996 to attend University. Before founding his own design studio in January 2003, Diez worked for Richard Sapper and then Konstantin Grcic. Since then, he has worked in various fields of design ranging from furniture and tableware to industrial design, as well as exhibition design for companies like Authentics, Bree, e15, Established and Sons, Gandiablasco, HAY, Moroso, Rosenthal, Thonet, Wilkhahn, and others. Many of his products have received international design awards, including the “Designpreis der Bundesrepublik Deutschland”, the “IF Gold award”, and the “red dot best of the best award”. Since 2007, he is Professor for Industrial Design at the HFG Karlsruhe.""