Hilary Greaves (born 1978) is a British philosopher, currently serving as professor of philosophy at the University of Oxford.

[1] From 2017 to 2022, she was the founding director of the Global Priorities Institute, a research centre for effective altruism at the university supported by Open Philanthropy.

[4] Her doctoral thesis was titled Spacetime Symmetries and the CPT Theorem and was supervised by Frank Arntzenius.

[4] Greaves' current work is on issues related to effective altruism, particularly in connection to global prioritisation.

Greaves has defended her longtermist position in terms of both utilitarian outcomes and intergenerational justice.