The Myrmidons are familiar from the story of the Trojan War because they were the troops Achilles led to Troy. They were called Myrmidons because it is said that they were originally ants and myrmidons comes from a Greek word for ant (μύρμηξ , ηκος).
The grandfather of Achilles was Aiacos whose son Phocus wound up on an island all alone. In response to his grief, Zeus, his grandfather, gave him company by turning the area ants into men and women. These Myrmidons were the first to build ships with sails (according to fragment 205 of Hesiod).