George Ellis is the Distinguished Professor of Complex Systems at the University of Cape Town, in the Department of Mathematics and Applied Mathematics. He co-authored The Large Scale Structure of Space-Time with University of Cambridge physicist Stephen Hawking, published in 1973, and is considered one of the world's leading theorists in cosmology. In 2004 he won the Templeton Prize.

Ellis was a vocal opponent of apartheid during the National Party reign in the 1970s and 1980s, and it is during this period that Ellis' research has focused on the more philosophical aspects of cosmology, for which he won the Templeton Prize.