Karl Oscar Isakson (16 January 1878, in Stockholm – 19 February 1922) was a Swedish painter who spent much of his professional life in Denmark where he is considered to be one of the fathers of Modernism.
He also showed great interest in literature reading Swedish authors such as Viktor Rydberg and Wilhelm Ekelund and Danish works by Søren Kierkegaard and Hans Christian Andersen.
[3] Before attending the Swedish Academy, Isakson worked as Carl Larsson's assistant, helping him with the frescos in the stairwell of the National Museum of Fine Arts in Stockholm.
In 1902, he travelled on a grant to Italy where he came into contact with Kristian Zahrtmann and his colony of Danish painters who introduced him to modern French trends, especially Paul Cézanne.
He returned to Copenhagen with Zahrtmann where he attend his art classes, meeting many young artists associated with the beginning of Modernism in Danish painting.
After a spell in Paris (1914), where he studied under Henri Le Fauconnier and André Dunoyer de Segonzac, his work progressed from theoretical Cubism to a more Nordic style where his temperament and physical imbalance left their traces.