Ash glimpses Ho-Oh at the end of the first Pokémon anime episode.
After Ash and Pikachu survive a storm and escape the Spearow flock, Ash looks into the sky and sees a large, rainbow-colored bird Pokémon flying overhead. The creature is Ho-Oh, a Legendary Pokémon whose identity was not immediately explained to viewers in the debut episode.
The sighting is notable because Ho-Oh was not part of the original first-generation Pokémon data available in the games when the episode aired. Its brief appearance therefore acted as an early mystery and helped suggest that the animated world extended beyond what players already knew from the Game Boy titles.
Ho-Oh later became central to Pokémon Gold and Silver, where it serves as the cover Legendary Pokémon of Gold. It also appears prominently in the 2017 film Pokémon the Movie: I Choose You!, which revisits and reimagines elements of Ash’s beginning.