Jillian Margaret Birt (born in Tambellup), is an Australian rock musician and architect. Birt was the keyboardist and vocalist of the alternative rock and pop band, The Triffids from 1983 to 1989. In 2008, The Triffids were inducted into the Australian Recording Industry Association Hall of Fame. Birt is married to The Triffids band mate Alan 'Alsy' MacDonald and the couple have three children, Connor, Oscar and Ebony. Both Birt and MacDonald have participated in reunions of The Triffids.
Jillian Margaret Birt was born in Tambellup, a rural agricultural region of Western Australia 317 km south east of Perth. Her parents were grain and sheep farmers, Philip Howard Birt and Margaret Brigid (née O'Neill). With her two older brothers, Birt was raised in a deeply religious household. Birt attended the local Tambellup Primary School and then boarded at the Methodist Ladies' College in Perth. After secondary education Birt studied fine arts and formed an all-girl punk band, What Are Little Boys Made Of. Later she was a member of Precious Title.