This article is about a world. For other uses, see Mercury (disambiguation).

In the Rocketmen setting, Mercury is inhabitable by humans, though it is hot. It is ruled by Empress Armada of Mercury.

The Mercurians are hot-tempered and warlike, and have been perpetual rivals with Venus. Mercurian legend states that Mercury and Venus were sisters, and the best of friends, despite their polarized temperaments. However, Venus betrayed her sister for the love of an Earth man. Venus banished Mercury, who was secretly carrying the man's child, to the first planet. Mercury raised her children to be both great warriors and mistrustful of Venus.

Despite their differences, they have recently joined with Venus and the rebels of Earth to form the Alliance of Free Planets to oppose the Legion of Terra and the Martians.