Chester Floyd Carlson (February 8, 1906 – September 19, 1968) was an American physicist, inventor, and patent attorney born in Seattle, Washington.

He is best known for inventing electrophotography, the process performed today by millions of photocopiers worldwide. 

Carlson began thinking about reproducing print early in his life. At age ten, he created a newspaper called This and That, created by hand and circulated among his friends with a routing list. His favorite plaything was a rubber stamp printing set, and his most coveted possession was a toy typewriter an aunt gave him for Christmas in 1916—although he was disappointed that it was not an office typewriter. 

While working for a local printer while in high school, Carlson attempted to typeset and publish a magazine for science-minded students like himself. He quickly became frustrated with traditional duplicating techniques. As he told Dartmouth College professor Joseph J. Ermene in a 1965 interview, "That set me to thinking about easier ways to do that, and I got to thinking about duplicating methods.

Xerography or electrophotography is a dry photocopying technique. Its fundamental principle was invented by American physicist Chester Carlson and based on Hungarian physicist Pál Selényi's publications.

Chester Carlson applied for and was awarded U.S. Patent 2,297,691 on October 6, 1942. The technique was originally called electrophotography. It was later renamed xerography to emphasize that, unlike reproduction techniques then in use such as cyanotype, this process used no liquid chemicals.

Carlson's innovation combined electrostatic printing with photography, unlike the dry electrostatic printing process invented by Georg Christoph Lichtenberg in 1778. Carlson's original process was cumbersome, requiring several manual processing steps with flat plates.

It was almost 18 years before a fully automated process was developed, the key breakthrough being use of a cylindrical drum coated with selenium instead of a flat plate. This resulted in the first commercial automatic copier, the Xerox 914, being released by Haloid/Xerox in 1960. Xerography is now used in most photocopying machines and in laser and LED printers.

According to en.wikipedia