Howard Staunton
Staunton's understanding of positional (strategic) play was far ahead of his rivals. His chess articles and books were widely read, and encouraged the development of chess. His Chess-Player's Handbook (1847) was a standard text-book for decades. He played and popularised two of the most important modern openings, the Sicilian Defence, and the English Opening. Staunton was a controversial figure in his time, and his chess writings could be spiteful. There is no doubt that he was the supreme figure in the chess world of the mid-19th century. His books, and his writing for newspapers and magazines, had world-wide influence.