William MacAskill (né Crouch; born 24 March 1987) is a Scottish philosopher, ethicist, and one of the originators of the effective altruism movement. He is Associate Professor in Philosophy at the University of Oxford, a researcher at the Global Priorities Institute at Oxford and Director of the Forethought Foundation for Global Priorities Research. MacAskill is also the co-founder and president of 80,000 Hours, the co-founder and vice-president of Giving What We Can, and the co-founder of the Centre for Effective Altruism.