The Reborn! manga and anime series, known in Japan as Katekyō Hitman Reborn! (Japanese: 家庭教師ヒットマンREBORN!, Hepburn: Katekyō Hittoman Ribōn!), features an extensive cast of characters created by Akira Amano. Set in a fictional town called Namimori in modern Japan, the series' protagonists are of Japanese descent. However, their connection to an Italian Mafia family results in a majority of other characters introduced being mainly of Italian descent, including most of its antagonists.

The story centers on middle school student Tsunayoshi "Tsuna" Sawada, who finds out that he is the heir to the most powerful Mafia family, the Vongola. The current Vongola boss thus sends his most trusted member, the titular character and infant hitman, Reborn, to train the future boss. Tsuna gradually becomes a more confident person and leader, while Reborn slowly recruits members into Tsuna's own Mafia family, which mostly includes Tsuna's schoolmates. Though they encounter new allies in the form of other hitmen and mafiosi, they also attract attention from those who want to annihilate the future boss of the Vongola Family. Enemies such as the Kokuyo Gang, a group of Mafia criminals, and Varia, an elite team of assassins, prove to be formidable challenges for Tsuna's new "family". When the story later shifts into an alternate future, nine years and ten months later, in which some of the characters are transported into, they have to adapt to a world where every Vongola member, as well as their allies, is being hunted down by a powerful rival family of that era, the Millefiore. The characters transported from the past into this future are joined by adult versions of the ones who have yet to be replaced with their younger selves.

Various publications that review manga series have mostly praised the eccentric cast of characters in Reborn!. Some attribute the story's humor to the peculiar characters, with one reviewer positively describing it is as an insane collection of characters. The story's shift into a darker and more serious tone by volume eight garnered even more praise, with some finding the characters being no longer simply used for slapstick comedy pleasing, and that the characters' evolving maturity is gratifying.