Ursula Klein (born 1952) is a German historian of science known for her cross-disciplinary work in history, philosophy and semiotics. Klein's concept of a paper tool has been widely applied, and is seen as marking a foundational change in scientific reasoning and practice in the history of chemistry in the early 19th century. Klein is a senior research scholar at the Max Planck Institute for the History of Science in Berlin, Germany. In 2016 she received the HIST Award for outstanding achievements in the history of chemistry from the American Chemical Society.