The Loves of Zeus: Callisto
In Greek mythology, the God Zeus (a.k.a. Jupiter in Roman mythology) had a huge number of lovers, including Io, Europa, Ganymede and Callisto, who gave their names to the four largest moons of the planet Jupiter. As mentioned in a previous post, Ganymede was the only male among them. But surprisingly there was another same-sex relationship as well. Callisto was a female follower of the Goddess Diana (also known as Artemis). In order to seduce her, Zeus shape-shifted into female form, posing as Diana herself in order to copulate with Callisto.