Marcantonio Colonna, 3rd Prince of Sonnino and 4th Marquess of Castelnuovo (Grande de España) (18 March 1724 – 16 August 1795) was an Italian nobleman, military and politician.

He was Prince of Sonnino, Marquess of Castelnuovo, Grandee of Spain, and Knight of the Order of Saint Januarius.

He became a courtier with the title of Gentiluomo di camera d'esercizio, and was very close to the young King Ferdinand IV during the regency of the Prince of San Nicandro and the Marquess Tanucci.

On June 16, 1765 he was sent as an extraordinary ambassador to Innsbruck, Austria, on the occasion of the marriage between the Infanta of Spain, Maria Luisa, daughter of Charles 3rd of Bourbon, and the then Archduke of Tuscany (future emperor) Pietro Leopoldo.

The events in Palermo had been triggered by food shortages, and the death of a popular leader at the hands of Fogliani's surgeon.