• English / United States: Tierno
• Japanese / Japan: ティエルノ
• Japanese (Romanized) / Japan: Tierno
• Japanese (TL) / Japan: Tierno

Tierno is a rival of the player in the Pokémon X and Y games for the Nintendo 3DS. He along with Trevor and Shauna are childhood friends who got their starter Pokémon from Professor Sycamore on the same day and then started their journey towards their respective dreams. They occasionally come together at events like the Pokémon Summer Camp to get each other up to speed on their journey.

Tierno is from from Hakudan City and he gets crushes on girls easily according to Shauna. His dream is to form a dance unit with my Pokémon. The rhythm and steps of a dance can be applied in battles as well which trainers often witness first hand in battles with him.

On the first day of the Pokémon Summer Camp, he was put in to Team Zenigame. He battled against Ash Ketchum and won. Tierno hoped that this win was the first step to the camp's Hall of Fame.