Turgesius (died 845) (also called Turgeis, Tuirgeis, Turges, and Thorgest) was a Viking chief active in Ireland who is said to have founded Drogheda in 911AD and Dublin. It is not at all clear whether the names in the Irish annals represent the Old Norse Thurgestr or Thorgísl.John O'Donovan and Charles Haliday independently identified him with Ragnar Loðbrók, but the identification is not generally accepted.
No history is recorded for Turgesius in his native Scandinavia, and knowledge of him is based on the history of his conquests as recorded in Ireland and Great Britain.