Estron-3

Estron-3 (the most pleasant-smelling asteroid in the Delta Galaxy) is the home planet of the Estronians, an all-female race of humanoid space aliens with shiny/metallic-looking skin and unusually-colored hairstyles for each member of the species.

Their only appearance was in "Bikini Space Planet!" (the first episode of Season 2), where they meet Johnny Bravo at Pop's Moon Palace and take him back to their home planet. As they explain to him, the Estronians have searched the galaxy looking for "the perfect male specimen" to serve as their king and satisfy their dating needs.

Trivia[]

The planet's name (and the name of the alien race) may come from "estrogen," an important female hormone.
They seem to be a less hostile pastiche of the alien women from Devil Girl from Mars, Fire Maidens of Outer Space and similar films, in that they also want to kidnap a promising male to help propagate their species but have no evil intentions towards Johnny or his home planet unlike the alien women in said films.