Karel Martens, born in 1939, is a Dutch freelance graphic designer and educator known for his experimental work in typography, book, and poster design. Considered one of the most influential Dutch designers working today, Martens co-founded Werkplaats Typografie, a postgraduate course in graphic design at the Arnhem College of Art. Renowned for his inventiveness and playful, experimental approach, he believes chance is important and mistakes are opportunities for new discoveries.