He is best known for playing Furio, the Sicilian hitman on the television show The Sopranos, but actor Federico Castelluccio has now landed a multimillion-dollar windfall from the refined world of art collecting.

Since his character left the HBO series 10 years ago, Castelluccio has gained an international reputation as a painter and expert in European art from the Baroque era.

Federico Castelluccio (second from right) with his fellow actors from Sopranos in 2002. Credit:Reuters

Castelluccio, 50, told the New York Post that an artwork he bought was mistakenly marked as an "18th-century Italian holy painting of Saint Sebastian".

"They had no idea who painted this," said Castelluccio, who was convinced that the work was a masterpiece from an earlier era.