Dennō Senshi Porygon

"Dennō Senshi Porygon" (Japanese: でんのうせんしポリゴン, Hepburn: Dennō Senshi Porigon, translated as "Computer Warrior Porygon", although more commonly "Electric Soldier Porygon") is the 38th episode of the Pokémon anime's first season. It only aired once in Japan on December 16, 1997.

In the episode, Ash and his friends find that there is something wrong with the Poké Ball transmitting device at the nearby Pokémon Center. To find out what is wrong, they must go inside the machine.

The episode is controversial because in a few scenes, it had repetitive flashing lights that caused epileptic seizures to several Japanese viewers. More than 600 children across Japan were taken to hospitals. The incident is referred to in Japan as the "Pokémon Shock" (ポケモンショック, Pokemon Shokku).

Because of the incident, the episode was banned and it has not aired since. The Pokémon anime went into a four-month pause.