Lamberto Visconti di Eldizio (died 1225) was the Judge of Gallura from 1206, when he married the heiress Elena, to his own death.
In 1207, Elena chose of her own will to marry Lambert, despite the fact that Pope Innocent III, to whom she and her state were pledged, had arranged a marriage with one of his own relatives.
In 1209, Comita III of Logudoro invaded Gallura and took Civita and briefly held sway over the hold kingdom, but Lambert and his Pisan allies soon retook it.
Elena died before 1220 and in that year, after the death of Torchitorio IV of Cagliari, Ubaldo arranged the marriage of his widow Benedetta to his brother Lambert.
Lambert thus controlled two giudicati comprising most of Sardinia, the one in the right of his now-deceased wife and the other in the right of his stepson William II.