Constantine I was the Giudice (Judge) of Gallura, one of the four medieval Sardinian judicates, ruling from probably before 1065 to sometime before 1100. He was likely a member of the Gherardeschi family of Pisa and governed the Gallura region of northeastern Sardinia on behalf of the Republic of Pisa.
Constantine is recorded as being alive in 1073, and a letter from Pope Gregory VII dated 1074 references him. He participated in the early introduction of Western monasticism into Sardinia and supported the Gregorian reform movement as well as the archdiocese of Pisa.
According to legend, Constantine was the father of Francesca Chica, who married Henry of Cinarca, one of the most powerful nobles on Corsica.
His reign is placed chronologically between Manfred of Gallura (his predecessor) and Torgodorio I (his successor), though the exact dates of his rule are uncertain.
