"Dennō Senshi Porygon", an episode of the Japanese television series Pokémon, induced epileptic seizures in 685 children.

"Dennō Senshi Porygon" is the 38th episode of the Pokémon anime's first season. During its sole broadcast in Japan on December 16, 1997, multiple scenes with flashing lights induced photosensitive epileptic seizures in children across the country. Over 600 people, mostly children, were taken to hospitals, while many others experienced more mild symptoms that did not necessitate hospitalization. The incident is referred to in Japan as the "Pokémon Shock" .

Pokémon, abbreviated from the Japanese title of Pocket Monsters, and branded in English as Pokémon the Series and Pokémon Horizons: The Series, is a Japanese anime television series, part of The Pokémon Company's Pokémon media franchise, which premiered on TV Tokyo in April 1997.

A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, or consciousness. Symptoms vary widely. Some seizures involve subtle changes, such as brief lapses in attention or awareness, while others cause generalized convulsions with loss of consciousness. Most seizures last less than two minutes and are followed by a postictal period of confusion, fatigue, or other symptoms. A seizure lasting longer than five minutes is a medical emergency known as status epilepticus.