Peter Albert David Singer AC is an Australian moral philosopher and the Emeritus Ira W. DeCamp Professor of Bioethics at Princeton University. He specializes in applied ethics and approaches ethical issues from a secular, utilitarian perspective. He is particularly known for his book Animal Liberation (1975), where he argues for vegetarianism, and his essay "Famine, Affluence, and Morality", advocating for donating to aid the global poor.

Singer has been a prominent figure in philosophical ethics, co-authoring The Point of View of the Universe (2014) with Katarzyna de Lazari-Radek, revealing his transition to a hedonistic utilitarian view. Throughout his career, he has been a preference utilitarian. Singer has chaired the philosophy department at Monash University, establishing its Centre for Human Bioethics. In 1996, he ran as a Greens candidate for the Australian Senate. In recognition of his work, he was named the Australian Humanist of the Year in 2004 and was one of Australia's ten most influential public intellectuals by The Sydney Morning Herald in 2005. He founded Animals Australia and the non-profit organization The Life You Can Save.