Although the Pokemon anime isn't exactly known for being a horror series, there are several episodes in the series that bring that goal into question. This is particularly evident in the original series, where the writers were still figuring out how much of the manga's much darker tone they wanted to adopt.
Even though Pokemon has found its voice and become a more consistent series, there are still several episodes in the newer seasons that are more horrific than would be expected for a children's series. And between those episodes, some are far scarier than others.
10 The Ghost of Maiden's Peak
One of the first truly scary episodes of the anime, The Ghost of Maiden's Peak follows the adventures of Ash, Brock, and Misty as they try to uncover the mystery of the ghost of a woman who turned to stone while waiting for her husband to return from war. However, this episode quickly devolves into true nightmare fuel with both Brock and James falling under the ghost's spell, which turns out to be a malevolent Gastly that can talk just as well as Meowth and can project illusions of a hybrid Pokemon to attack anyone that comes after them.
9 Pokemon Shipwreck
The S.S. Anne is an iconic symbol of the Kanto region in both video games and anime, but for vastly different reasons. On the one hand, the S.S. Anne in Red & Blue is a mini-dungeon of sorts that becomes inaccessible once completed and the player has obtained HM01 Cut. But in the anime, it is the source of a multi-episode storyline that involves Ash trading away his beloved Butterfree for a Raticate as well as the ship sinking to the bottom of the ocean. The episode Pokemon Shipwreck not only sees children having to escape from a sunken ship, but the episode ends with them being attacked by rampaging Gyarados.
8 Mystery At The Lighthouse
Based on the Ray Bradbury novel The Foghorn, which would go on to inspire the Godzilla franchise and the 1953 film The Beast From 20,000 Fathoms, Mystery At The Lighthouse begins with Ash catching his seventh Pokemon, a random Krabby that would later become one of his most powerful Pokemon in the Kanto League. But this turns into a monster movie very quickly.
After Team Rocket attacks a giant Dragonite that walks in from the ocean Godzilla style, it proceeds to annihilate the lighthouse before walking off as if nothing had happened. The lighthouse's owner, Bill, marvels at the destruction as if his life wasn't just in serious danger.
7 Abra and The Psychic Showdown
Of all the gym leaders in Kanto, Sabrina is easily the most deadly in the anime. Aside from having a very creepy-looking doll that represents her lost childhood persona, she also has psychic powers that can turn people into dolls or shrink them down to the size of toys so that she can "play with them." One of the most disturbing aspects of this episode, however, is the fact that Sabrina forces her Abra to evolve with just her mind, then proceeds to torture Ash's Pikachu until the pair yield and agree to be her playthings.
6 The Tower of Terror
Immediately following Ash's humiliating defeat against Sabrina, he decides that he needs to capture a Ghost-type Pokemon if he is to have a chance at defeating her Kadabra and goes to the Pokemon Tower to track one down. While the group does encounter a Gastly, Haunter, and Gengar, Ash is able to befriend the Haunter long enough for it to agree to go with him, but not before both Ash and Pikachu briefly die and become ghosts. They use this to their advantage in haunting Brock and Misty until they are brought back to life.
5 Scare At The Litwick Mansion
There have been several haunted house-style episodes in the Pokemon anime, but none are quite as chilling as the Unova series episode Scare At The Litwick Mansion. After being caught in a storm, Ash, Cilan, and Iris seek shelter in an abandoned mansion, only to discover that it is haunted by a group of Litwick that Team Rocket is planning to use to capture Pikachu. The most horrifying part of this episode, however, is the fact that the Litwick are slowly killing Team Rocket while they are trying to do their work, which results in some truly scary imagery of an emaciated Jesse and James.
4 Seeking Shelter From The Storm
Following almost the exact same story beats as Scare At The Litwick Mansion, this Kalos series episode sees Ash, Clemont, Bonnie, and Serena taking shelter from a storm in a slightly less abandoned mansion, only to be haunted by a Meowstick that inhabits the house.
While the episode is a little more heart-wrenching than scary, with the Meowstick wanting to return a pendant to their friend that recently died, there are many moments that are common in haunted house stories and have the potential to scare young children.
3 Ghoul Daze
Pokemon has dealt with death in the series before, but the Sinnoh series episode Ghoul Daze is one of the more horrific. While at a Pokemon summer camp, Ash and his friends come across the spirit of a young girl who haunts the group and nearly causes Conway to jump to his death before opening a mysterious portal that she wants to suck the students into. In the English dub, this portal is said to lead to the afterlife, but in the original Japanese dub, this little girl instead opened a portal to hell. Neither version ever explains where she came from or why she was doing what she did.
2 The Old Chateau
The spin-off short series Pokemon Generations covers many different characters and regions seen throughout Pokemon's life, starting with the Kanto region and ending in the Kalos region. But one particular episode, named The Old Chateau, covers the titular chateau as seen in Pokemon Diamond & Pearl, as well as Cheryl and her Chansey. In this short episode, the pair stumble upon the house while seeking shelter, only to be attacked by the ghost of a butler, a little girl, and the image of a very large Haunter, with their fates never being shown by the end of the episode nor the series.
1 The Aura Storm
There have been several monstrous Pokemon in the anime series, the majority of which are either under the control of another person, such as Sycamore's Garchomp, but one that was much more terrifying was Korrina's Lucario during the episode The Aura Storm, as well as several episodes following this. After learning to Mega Evolve, it quickly becomes apparent that Lucario can't control its power and proceeds to nearly kill both Ash and Pikachu in its rage, only to be stopped by Korrina's grandfather and his own Lucario.