George Edward Fox (born December 17, 1945) is a researcher at the University of Houston and, with Carl Woese in the early 1970s, was the first scientist to classify Archaea as a separate domain of life within the three-domain system. Fox and Woese also introduced the idea of a progenote as a primordial entity in the evolution of life. While with Woese, he pioneered use of comparative analysis in prediction of RNA secondary structure. Using comparative analysis, he also recognized the limitations that RNA sequences could provide when identifying closely related species. His research centers around understanding the early evolution of life. Fox contends that one of the earliest components of the genetic machinery to appear in a form bearing resemblance to its modern equivalent was the ribosome. His research is actively involved in the search for biosignatures on Mars.