Keldeo (Japanese: ケルディオKerudio) is a Water/Fighting-typeMythical Pokémon from Generation V. Keldeo used to live in a forest that burned down in a terrible fire. Cobalion, Terrakion, and Virizion found Keldeo and took it in as their own, making it the fourth, but secret member of the Musketeer Trio. It resembles d'Artagnan in the novel The Three Musketeers by Alexandre Dumas. It has a signature move that is called Secret Sword. Teaching Keldeo Secret Sword changes its form from its Ordinary Forme to its Resolute Forme.
Keldeo resembles a foal or small unicorn referring to the horn on its head. It is mainly pale in color with light blue fur covering its neck and the back of its head. Its tail is also light blue in color. It has long, dark blue eyebrows and a red mane. On the ends of its legs are dark blue hooves. In its resolute form it's mane changes to the colours of the other members of the musketeer trio's colours.
Keldeo is based on a Kelpie, a supernatural water horse that appeared as a lost pony, that dragged people to their deaths by drowning them.
Keldeo may also be based on D'Artagnan from The Three Musketeers, as Keldeo is part of the Muskedeer quartet. Just like D'Artagnan from the book, Keldeo is similar as it is possibly the youngest of the quartet.
Keldeo is only obtainable through a current event and hacking the game.