Cathrine Anne Coolahan ONZM (née Castle; 2 November 1929 – 3 January 2025) was a New Zealand commercial artist, fashion illustrator, and printmaker.

[2][3][4] Coolahan was born in Sydney, Australia to Roderick Castle, a printer, and Dorothy Vera Evans, a homemaker.

[5] She attended Neutral Bay Girls Junior High School and then studied art at the East Sydney Technical College from 1945 to 1950.

[5] In 1954, Coolahan moved to rival Wellington advertising agency Carlton Carruthers du Chateau and King.

[7] She was appointed an Officer of the New Zealand Order of Merit in the 2007 Queen's Birthday Honours, for services to the arts.