Elizabeth Helen Blackburn (born 26 November 1948) is an Australian–American Nobel laureate who is the former president of the Salk Institute for Biological Studies. In 1984, Blackburn co-discovered telomerase, the enzyme that replenishes the telomere, with Carol W. Greider. For this work, she was awarded the 2009 Nobel Prize in Physiology or Medicine, sharing it with Carol W. Greider and Jack W. Szostak, becoming the first Australian woman Nobel laureate. She also worked in medical ethics, and was controversially dismissed from the Bush administration's President's Council on Bioethics. 170 scientists signed an open letter to the president in her support, maintaining that she was fired because of political opposition to her advice.