Giulio Genoino (born c. 1565 in Cava de' Tirreni), the 'mind of Masaniello', was a key figure in the 7 July 1647 popular insurrection against Spanish authority in the Kingdom of Naples.

A priest, lawyer, and academic, Genoino had for three decades attempted to influence constitutional change to involve the Third Estate in the government of the city.

Despite being a representative of the king to Naples, he was accused of spreading sedition and instigating riots during unrest in 1585 and 1620.

After periods of imprisonment and exile, and then in his 80s, he returned to Naples and began advising the fisherman and smuggler Tommaso Aniello—later known as Masaniello—a popular figure among the city's populace.

Genoino was the real power behind the popular movement, and supplied the directionless and illiterate Masaniello with advice and a coherent policy.