Otto Pfenninger (5 April 1855 – 20 March 1929)^[1] was a founding member of the Swiss Photographers Association (1886) and a pioneer of colour photography. He moved to Brighton, England where he developed his career as a photographer.

In 1906, Pfenninger built a special camera to his own design using 3-colour separated plates from which full-colour photographic images could be created. That summer Pfenninger used this tri-colour, single exposure camera to create some of the first colour photographs, using the parks and beaches of Brighton as scenes.^[2] His camera was based upon J.W. Bennetto's one-shot camera of 1897 in which three separation negatives were obtained at a single exposure. Pfenninger tried to use the same system but found that the refracted image was shorter from top to bottom,^[3] his solution was to add a glass plate at the same angle, but opposite direction, to the Bennetto reflector.

In 1921,^[4] under the pseudonym O. Reg, he wrote Byepaths of Colour Photography in which he discusses in technical detail, the history and theory of developments in subtractive colour photography.