Paul Kayser (22 September 1869, in Hamburg – 23 September 1942, in Donaueschingen) was a German painter and graphic artist.
He began with an apprenticeship as a decorative painter at the firm of Wirth & Bay then, from 1886 to 1889, attended the Königliche Kunstgewerbeschule München, followed by the . From 1890 to 1894, he worked as a decorative painter in Hamburg.
In 1902, he married Melanie Hertz, daughter of the physicist Heinrich Hertz, and they had two children. At that time, he was a private art teacher.
From 1906 to 1939 (interrupted by service in Schleswig during World War I) he taught at the art school operated by . Due to the destruction resulting from World War II, he left Hamburg in 1941 to settle in Donaueschingen, on the Swiss border, where he died one year later.
He was a founding member of the and, from 1897, a participant in the, a group of young artists and writers, modelled on the Munich Secession. He was also a member of the . His style was heavily influenced by Albert Marquet, whom he had met in 1909, and reunited with during a trip to Paris in 1933. His notable works include two large paintings that were created as decorations for the ocean liner SS Imperator.
His works were part of a major exhibition in 2019: Hamburger Schule – Das 19. Jahrhundert neu entdeckt at the Hamburger Kunsthalle.