Geraint F. Lewis is a Professor of Astrophysics at the Sydney Institute for Astronomy, part of the University of Sydney's School of Physics. The focus of his research is cosmology and the dark side of the universe, namely the dark matter and dark energy that dominate cosmological evolution. He has published more than three hundred academic papers and is an acclaimed teacher.

He also has a significant outreach profile, writing regularly for New Scientist and The Conversation, as well as regularly speaking publicly on all aspects of cosmology and astronomy, including speaking that the Royal Institution in London. He also has extensive experience interactions with the media, including podcast, radio and television experience. He currently is Deputy Director of the Sydney Informatics Hub, developing the infrastructure and knowledge-base to support big data, informatics, deep learning and artificial intelligence at the University of Sydney.