Who came up with the three domain system?

The three-domain system was proposed by Carl Woese, a microbiologist at the University of Illinois, in 1990. His research on ribosomal RNA (rRNA) sequences led to the discovery that prokaryotes consist of two distinct groups—Archaea and Bacteria—which are as genetically different from each other as they are from Eukarya. This finding prompted Woese to classify life into three domains: Archaea, Bacteria, and Eukarya.