In 1994, at the age of 17, Lynskey won her first professional acting role as Pauline Parker in the Peter Jackson film Heavenly Creatures, based on the 1954 Parker-Hulme murder, opposite Kate Winslet. Over 500 young actors auditioned for the role before Lynskey was cast with Jackson recalling "we knew if we cast an intelligent person, then they were going to hit it. Melanie's also very enigmatic. So what we were looking for was an actress who has that kind of aspect to her...where you can film somebody sitting in a room, doing nothing, and they're still fascinating to watch. We found that in Mel."