Lasus of Hermione (Greek: Λάσος ὁ Ἑρμιονεύς) was a Greek lyric poet who lived in the 6th century BC. He was born in the city of Hermione in the Argolid region. He was active in Athens during the time when the Peisistratids ruled. A work called De Musica by Pseudo-Plutarch says Lasus made improvements to the dithyramb hymn.

By changing the music and rhythm, Lasus helped turn the dithyramb into a carefully designed choral song that was played with multiple flutes. This form became more detailed and imitative, and it covered topics beyond the stories of Dionysus. Lasus made the dithyramb more popular by starting contests to find the best poem of this type.

In some of his poems, Lasus avoided using the letter "s" because of its hissing sound. A few lines from one of his poems, a hymn to Demeter of Hermione, are recorded in a work by Athenaeus (xiv. 624 E).

According to Herodotus, Lasus discovered that Onomacritus had created fake copies of the oracles of Musaeus. Lasus is also said to have written a treatise on music, but most of it is now lost.