Karl David Ilgen (26 February 1763, born in Sehna, a village near Eckartsberga – 17 September 1834, Berlin) was a German Protestant Old Testament scholar and classical philologist.
He studied theology and philology at the University of Leipzig, and was later appointed rector at the munincipal gymnasium in Naumburg (1789). In 1794 he became a professor of oriental languages at the University of Jena. From 1802 to 1831, he was rector of the Landesschule Pforta.
Ilgen is credited as the first to use the term "epyllion" in classical literature, coining the term in 1796 when describing the Homeric "Hymn to Hermes".