Margaret of Navarre (French: Marguerite, Spanish: Margarita, Italian: Margherita) (c. 1135 – 12 August 1183) was the queen consort of the Kingdom of Sicily during the reign of William I (1154–1166) and the regent during the minority of her son, William II.
She was a daughter of King García Ramírez of Navarre and Marguerite de l'Aigle. She was married at a young age to William, while he was still a prince, the fourth son of Roger II of Sicily. According to the Palermitan archivist Isidoro La Lumia, she was, in her later years, bella ancora, superba, leggiera ("still beautiful, proud, light").
During the reign of her husband, Margaret was often ignored by the king, who did not particularly like her and certainly did not love her. However, she was a stronger person than he and several times convinced him to act where he was wont to be passive. She had an infatuation, perhaps mutual, with Maio of Bari, the king's ammiratus ammiratorum, and they were often allied in trying to subvert the opponents of the king, though she was once detained with two of her sons by Matthew Bonnellus during a revolt.
By William she had a total of four sons: Roger IV, Duke of Apulia, predeceased his father; Robert, also predeceased his father; William, the successor; and Henry, Prince of Capua.
It was William's will that his eldest son succeed him and his second son receive the principality of Capua. This was done and, on the day of William II's coronation, Margaret declared a general amnesty throughout the realm. The new regent also revoked her late husband's least popular act: the imposition of redemption money on rebellious cities. Margaret's first order of business was to appoint a strong hand to the vacant position of admiral (Maio having died). She promoted the caïd Peter, a Moslem convert and a eunuch, much to the annoyance of many a highborn nobleman or palace intimate.