Magical girls (魔法少女, mahō shōjo^?, also known as mahou shoujo or majokko) belong to a sub-genre of Japanese fantasy anime and manga. Magical girl stories feature young girl heroes with superhuman abilities, forced to fight evil and to protect the Earth. They often possess a secret identity, although the name can just refer to young girls who follow a plotline involving magic and a transformation (such as Full Moon o Sagashite and Sailor Moon). Ojamajo Doremi features magical girls as protagonists, but its plot differs from the standard as the girls use magic for friendship, behavior and achieving goals, rather than for attacking antagonists. The Japanese language identifies magical girls as majokko (魔女っ子^?, literally "witch girl"), though this term does not generally apply to modern magical-girl anime. Sally, the Witch (1966) counts as the first magical girl anime.

Magical boys occur much more rarely, but one can readily identify them: they operate along similar lines (as with D.N.Angel, Mei no Naisho, and Negima!). Magical girls generally differ from catgirls and from magical girlfriends. Sometimes the catgirl and magical girl character types cross over; the magical girl may have cat-ears and -tail as part of her costume, or a catgirl could have some form of magical powers. Examples of these include Tokyo Mew Mew and Hyper Police. A magical girl and a magical girlfriend typically differ in that the magical girlfriend is not the protagonist.