Boris Christoff (Bulgarian: Борис Кирилов Христов, official transliteration Boris Kirilov Hristov pronounced [bɔrˈis ˈkirilɔf ˈxristɔf]; 18 May 1914 – 28 June 1993) was a Bulgarian opera singer, widely considered to have been one of the greatest basses of the 20th century.