Ferdinand van den Eynde, 1st Marquess of Castelnuovo (mid-17th century – 1674) was an Italian nobleman and magnate of Flemish descent.

He was the son of Jan van den Eynde, an extremely wealthy Flemish merchant who had become one of the richest men in Naples through trading and banking.

[9][7][10] The Van den Eynde were related to notable Netherlandish artists such as Brueghel, Jode, and Lucas and Cornelis de Wael.

[23] However, Van den Eynde died of consumption the same year,[24] and his huge collection passed to his daughters, Elisabeth and Jane (Giovanna).

Van den Eynde's daughters, Giovanna and Elisabeth, married the heirs of two of the most powerful Italian families, the Colonna and the Carafa.