Eevee can currently evolve into eight different Pokémon.
Eevee’s unstable genetic code allows it to change into species associated with different elemental types. Its original three evolutions are Vaporeon, Jolteon, and Flareon, introduced alongside Eevee in Pokémon Red and Blue.
Later games added Espeon and Umbreon in Pokémon Gold and Silver, Leafeon and Glaceon in Pokémon Diamond and Pearl, and Sylveon in Pokémon X and Y. These eight forms are commonly called Eeveelutions.
The number is sometimes given incorrectly as three because those were the only options in the first generation. It is also distinct from Eevee’s partner forms and Gigantamax form, which are not additional evolutionary species.