What friend did Athena kill by accident?

Athena accidentally killed her friend Arachne during a weaving contest. Arachne, a mortal, challenged the goddess to a contest, boasting of her skill. When Arachne's work was deemed superior, Athena, enraged and jealous, struck her down. In some versions of the myth, Athena transforms Arachne into a spider, condemning her to weave for eternity.