White Knight Mk12 is a chess playing program for the BBC Microcomputer. It was developed by Martin Bryant. This program won the European Microcomputer Chess Championship in 1983, and was commercially released, in two versions (Mk 11 and Mk 12) for the BBC Micro and Acorn Electron in 1984 by BBC Soft. White Knight featured a then-novel display of principal variation – called "Best line" – that would become commonplace in computer chess.