Invercargill born Molly Macalister was a passionate advocate for sculpture at a time when very little was made or exhibited in New Zealand. A founding member of the New Zealand Society of Sculptors and Associates (1961) and honorary life member from 1979, she was the prime mover behind the 1971 international sculpture symposium held in Auckland. Her public commissions include Maori Warrior, 1964 in Auckland's Queen Street and Little Bull, 1967 in Hamilton Gardens. These two monumental bronzes have a quiet strength and power, conveying deep respect for their subjects - a characteristic of all Macalister's work. Other works from this period are stone carvings for the ark in the Auckland synagogue and a bust of John A Lee for the Auckland Public Library.

In 1952 Macalister was a finalist in a competition for a sculpture of the Unknown Political Prisoner, and her maquette was exhibited at the Tate Gallery in London. With fellow sculptors Anne Severs and Alison Duff she began using cast and moulded concrete. The three women exhibited at Auckland City Art Gallery in 1959. Influenced by the work Henry Moore and the Italian sculptor, Marino Marini whose work she had seen at Auckland City Art Gallery in 1956, Macalister's sculpture increased in scale. In 1962 and 1969 she travelled extensively with her husband to Europe, America and Japan.

Molly Macalister died in Auckland on 12 October 1979. She was survived by her husband, George Haydn and her son. In one of several published tributes, Colin McCahon wrote: Let us sing for Molly with the sculptured head - a head bearer for the many heads she made for the Queen Street Warrior: beautiful heads and perhaps she never really knew what she created. Few artists if any ever know this.