Karl Gustaf Nilson was a Swedish visual artist born in Falun. He studied at Valands Konstskola in Gothenburg, Atelier 17 in Paris and Konstakademien in Stockholm. He was a professor of printmaking at Konsthögskolan from 1983 to 1993, and previously taught colour theory at Konstfack from 1972 to 1983.

KG Nilson is best known for his colourful, geometric compositions. He came into contact with Josef Albers and translated his book Interaction of Colours into Swedish. He subsequently wrote several books on colour and developed his own colour theory, first published in the book Färglära in 1982. The book is used at many art schools and was reissued in 2018 under the title Om färg.

Many of KG Nilson’s paintings are oval, with the dynamism of the image emerging as rhombuses and larger forms take shape while the painting is being read. His colour constructions were often accompanied by scores featuring staves, circles and squares. He experimented with geometric forms covering the entire surface.

Represented at Moderna museet in Stockholm, Amos Andersons konstmuseum in Helsinki, Muzeum Sztuki in Łódź, the British Museum in London, the Kupferstichkabinett in Dresden, Kalmar konstmuseum, Nordiska Akvarellmuseet, Norrköpings konstmuseum, Örebro läns landsting, Nationalmuseum in Stockholm and several other museums in Sweden.