Roger I (Roger Guiscard), c.1031–1101, Norman conqueror of Sicily; son of Tancred de Hauteville (see Normans). He went to Italy in 1058 to join his brother, Robert Guiscard, in conquering Apulia and Calabria from the Byzantines. Between 1061 and 1091 he took Sicily from the Arabs. After the fall (1072) of Palermo he became count of Sicily under Robert's suzerainty. Robert's death (1085) left Roger the most powerful Norman lord in S Italy, and he ruled the various ethnic groups in his feudal domain justly and tolerantly. In 1098, Roger was made papal legate. His son succeeded him as Roger II.
See J. J. Norwich, The Other Conquest (1967).