John of Gallura

John Visconti (c. 1229 – May 1275) was judge of Gallura from 1238. The son of Ubaldo I Visconti of Cagliari, he inherited Gallura under his cousin Ubaldo II's will of 1237 and recovered it from Ubaldo's widow Adelasia and her second husband.

In 1254 he joined Pisa against the judge of Cagliari, and when that giudicato was partitioned in 1258 he annexed a third of its lands. He later fought in the Guelph-Ghibelline wars.

In 1275 Pisa expelled him for joining the Guelphs, and he joined forces with Lucca and Florence to take Montopoli castle. He died at San Miniato the same year, and his son Nino succeeded him.