Pasquale Del Pezzo, Duke of Cajanello, (1859–1936), was "the most Neapolitan of Neapolitan Mathematicians".

He was born in Berlin (where his father was a representative of the Neapolitan king) on 2 May 1859. He died in Naples on 20 June 1936. His first wife was the Swedish writer Anne Charlotte Leffler, sister of the great mathematician Gösta Mittag-Leffler (1846-1927).

At the University of Naples, he received first a law degree in 1880 and then in 1882 a math degree. He became a pre-eminent professor at that university, teaching Projective Geometry, and remained at that University, as rector, faculty president, etc.

He was mayor of Naples starting in 1919, and he became a senator in the Kingdom of Naples.

His scientific achievements were few, but they reveal a keen ingenuity. He is remembered particularly for first describing what became known as a Del Pezzo surface. He might have become one of the strongest mathematicians of that time, but he was distracted by politics and other interests.