He also works extensively with portraits and has among others painted the three generations of Norwegian monarchs involved in the events of WWII, Dame Vera Lynn and Elizabeth II.

In his works, Kolby debates themes such as racism, handicapped people's rights, environmental problems, sexual abuse of children, war and political conflict.

Kolby received death threats when he was about to exhibit his historical motif The murder of Pope John Paul I in 1997 and withdrew the artwork from the show.

[4] After Anders Behring Breivik’s 2011 Norway attacks in Oslo and at Utoya on 22 July Kolby painted a Yara International bag of artificial fertilizer to debate extremism and the individual's responsibility of using or abusing available technology.

[7][8][9][10] To the celebrations of the 25th year Consecration Jubilee of the reign of Norway's Harald V and Queen Sonja in 2016[11] Kolby was commissioned by Samlerhuset in 2016 make a painting as a gift the Crown Regalia Museum in the medieval Archbishop's Palace, Trondheim.