Ho-Oh appeared at the end of the first Pokémon anime episode.
In “Pokémon, I Choose You!”, Ash sees a large, colorful bird Pokémon flying across the sky after a storm. The unidentified Pokémon is later recognized as Ho-Oh, a Legendary Pokémon associated with the Johto region and the Pokémon Gold and Silver games.
Ho-Oh’s early anime appearance was notable because it occurred before the character had been formally revealed in the first-generation games. This created one of the series’ earliest mysteries and gave viewers a glimpse of a Pokémon connected to the next generation.
Ho-Oh is a dual Fire- and Flying-type Pokémon. It is traditionally paired with Lugia, which is associated with the sea and appears prominently in Pokémon Silver and later Pokémon stories. Moltres and Articuno are also legendary bird Pokémon, but neither is the bird seen in the episode’s final scene.