Pierre-Étienne Piestre, known as Eugène Cormon (5 May 1810 – March 1903), was a French dramatist and librettist.

[2] Cormon wrote dramas, comedies and, from the 1840s, libretti; around 150 of his works were published.

He was stage manager at the Paris Opéra from 1859 to 1870, and administrator of the Théâtre du Vaudeville from 1874.

[3] The Fontainebleau act as well as the auto-da-fé scene of Verdi's opera Don Carlos is based in part on Cormon's 1846 play Philippe II, Roi d'Espagne ("Philip II, King of Spain").

[4][5] At the Moscow Art Theatre in 1927 the seminal Russian theatre practitioner Constantin Stanislavski staged Cormon's melodrama The Gérard Sisters (The Two Orphans), which he co-wrote with Adolphe d'Ennery.