Medea of Colchis

Queen Medea of Argos was the one-time wife of Jason. Jason left her to marry Glauce.

Sometime after his betrayal, Medea killed Glauce and Jason's children. This event caused Jason to delve into severe alcoholism, which was taken advantage of by Castor. (HTLJ: "Once a Hero")

Background information
Another character named Medea appeared in "Medea Culpa," although there appears to be little similarity.

Both characters were based on the mythological Medea (Greek: Μήδεια), a priestess of Hecate who originated from Colchis. The children she killed were her own with Jason, although that wasn't specified in the episode.