Tolomeo Gallio (also spelled Gallo and Galli; 25 September 1527 – 3 or 4 February 1607) was an Italian Cardinal.

In the time of Pope Gregory XIII, he acted as papal secretary of state (in office 1572 to 1585), having a key role in the curia.

[1] He built the Villa d'Este, in his birthplace Cernobbio, in 1568, as a summer residence; and the Palazzo Gallio of Gravedona.

Tolomeo in 1595 acquired the County of Alvito (later Duchy) in southern Lazio, which he assigned to his nephew Tolomeo; the Gallio family held the fief until 1806.

While bishop, he was the principal consecrator of:[2] and the principal co-consecrator of:[2]