Pierre Willems (January 6, 1840, in Maastricht – February 23, 1898, in Leuven) was a Dutch philologist and historian of Ancient Rome.
On his return in 1865 he was appointed professor of Latin philology at the Catholic University of Leuven; here he spent the remainder of his life, the only events being his lectures and his works.
His two chief works are Le droit public romain (Roman Public Law), first issued under the title, Les antiquités romains envisagées au point de vue des institutions politiques (Louvain, 1870; 7th ed.
It was by the exercise of the curule magistracies that the plebs entered the Senate, in fact after 354-200; a plebiscite proposed by the Tribune Ovinius and accepted at the end of the fourth century hastened the introduction of the plebeians, and, in short, made the Senate an assembly of former magistrates.
He assisted in the foundation of the second Belgian periodical for classical philology, Le Musée belge (1897), and organized a Societas philologa, at Louvain, one of the oldest members of which was the Liège professor, Charles Michel, author of the Recucit d'inscriptions grecques (1900–12).