Cesare Alessandro Scaglia (1592–1641) was an Italian cleric and diplomat of the 17th century. He was also abbot of Staffarda Abbey.
He served in Rome, Paris and London as an ambassador for the House of Savoy, also collecting antiquities for the duchy. He was also in the service of Philip IV of Spain in London (acting on behalf of Spain up to 1636) and assisted Charles I of England in negotiating a commission on the subject of Cupid and Psyche from Jacob Jordaens for the Queen's House in Greenwich. However, his support of Spain led to tensions with Victor Amadeus I when he succeeded to the Duchy of Savoy in 1630, meaning that soon afterwards Scaglia retired to Brussels and Antwerp, both in the Spanish Netherlands.
Peter Paul Rubens (a diplomat himself) described Scaglia as "a man of the keenest intellect". Scaglia was an art collector and commissioned a portrait, a Virgin and Child (showing Scaglia himself praying to them) and a Deposition (intended for his tomb) from Antony van Dyck whilst in Brussels and Antwerp. There were a total of five van Dycks in his collection, which also contained works by Pieter Snayers and Antonio Tempesta. In or after 1637, he entered the Recollects Convent in Antwerp, where he died.