Rudolf Eric Koertzen (/ˈkɜːrtsən/; 26 March 1949 – 9 August 2022) was a South African international cricket umpire. A cricket enthusiast since his youth, he played league cricket while working as a clerk for South African Railways. He began umpiring in 1981, before becoming a full-time official eleven years later. In an international career spanning 18 years, he officiated in a record 331 matches and is only behind Aleem Dar in officiating as an umpire in most international matches.