Demetrios Lialios (Δημήτριος Λιάλιος, Patras, 1869 - 13 March 1940) was a Greek composer.
He studied at the Hochschule für Musik und Theater München under Ludwig Thuille.
He was possibly the first modern Greek composer to write chamber music.
[1] His oeuvre includes an opera, a requiem, 22 orchestral compositions, 14 chamber music works, and 2 compositions for Greek Orthodox liturgy.
His Requiem in B minor, titled Missa pro Defunctis is perhaps the first large-scale modern Greek choral work.