Robert of St. Albans

Robert of St Albans was an English Templar Knight who converted to Islam from Christianity in 1185.
In 1187, Robert fought for Saladin against the Crusaders during the Battle of Hattin and the Siege of Jerusalem. Robert died the same year outside of Jerusalem.
According to Roger of Howden, Robert promised to deliver Saladin the city of Jerusalem, married his niece, became a Prince and was made a leader of Saladin's army. Helen J. Nicholson calls into question the validity of Howden's account, stating that it "reads like a fairy tale".