Mats Theselius is a Swedish furniture designer, artist, and interior architect, born in 1954 in Stockholm. Theselius studied interior architecture at Konstfack from 1979 to 1984 and shortly after graduating, he made his breakthrough with the groundbreaking chair "Älgskinnsfåtöljen," a cylindrical armchair made of sheet iron and moose leather. This chair marked the beginning of a long and uninterrupted career, largely in collaboration with the legendary furniture producer Sven Lundh (who also launched Jonas Bohlin's concrete chair, Concrete) at Källemo in Värnamo. Following this, several renowned pieces were created, including the showcase cabinet National Geographic, distinguished by its characteristic yellow color and named after the magazine of the same title, as well as the chairs Rex, Ingo, and Bruno.

In addition to his prolific career in design, Mats Theselius served as a professor at the University of Gothenburg's School of Design and Crafts in the 1990s. In 1997, he was honored with both the Bruno Mathsson Prize and the Torsten and Wanja Söderberg Prize. Mats Theselius was elected to the Royal Swedish Academy of Fine Arts in 2011.