Although
Osamu Tezuka is undeniably the most influential
manga and
anime artist of all, only a few of his works have been translated into English. Thus, recurring elements that would be immediately recongized by his fans in Japan are lost on an English-speaking audience. Chief among these is the reuse of characters in different contexts. Several of his early works shared
heroes and
villains. More frequently, major characters in one work would reappear elsewhere in minor or supporting roles.
It should be emphasized that, when two pieces of manga share a star character, it doesn't mean that it's the same person within the fiction. Stars generally don't recognize each other from their other appearances, and they not infrequently die during the story only to reappear in later works. It's best to think of them as virtual actors, playing similar but unrelated roles in different stories. This may seem odd at first, and it's certainly not a common phenomenon in manga, but when you think about it, it's pretty common in American funny animal cartoons. Daffy Duck has played analogs of Robin Hood and Buck Rogers; Mickey Mouse plays the title role in both The Brave Little Tailor and The Sorcerer's Apprentice.
A few of the more notable stars are:
Kenichi: A young boy, compassionate and pure of heart. Kenichi is the standard hero of Tezuka's early works, and the first of Tezuka's stars. He's one of the main characters in Tezuka's seminal sci-fi trilogy consisting of Lost World, Metropolis, and Next World, and plays a significant role in Jungle Taitei.
Higeoyaji, aka Shunsaku Ban or Mr. Mustache: Rotund and fatherly in appearance, with a large drooping mustache, but not to be underestimated: he has a keen mind and great willpower. He appears in a lot of early Tezuka, usually as a detective. Sometimes he's related to Kenichi, providing the wisdom of experience to balance Kenichi's youthful impulsiveness. He's best known as Astro Boy's teacher, although this was not his first role.
Acetylene Lamp: Mean-spirited and irritable, his thin-lipped mouth is nearly always bent into an ear-to-ear smirk or an equally wide scowl. The most notable thing about him is that he's sometimes drawn with a lit candle sticking out of the back of his head. (In this, he's based on a classmate of Tezuka, who had a dent in the back of his head that, according to his teasing classmates, could hold a candle upright.) He appears as early as Lost World and plays a major role as a Gestapo agent in Adolf.
Ham Egg: A seedy but cunning man capable of the most desperate acts. Chiefly recognizable by his big toothy grin; even when he frowns, he keeps his teeth exposed. He appears as a cruel hunter in Jungle Taitei, and he has a significant role in Adolf as well (as Akabane of the Japanese secret police). He's sometimes paired with Lamp to form a comedic villain duo, Ham Egg's low coarseness playing off of Lamp's irritability.
Rock Home: Originally a boy detective in his own manga (his name is apparently a shortened version of Sherlock Holmes). He's a counterpoint to Kenichi: they're similar in their childish simplicity, but in Rock's case it has darker things underneath. In volume 2 of Phoenix, for example, his unwavering faith in technology makes him the chief antagonist. As such, he's one of the few characters to appear as both hero and villain. Recognizable chiefly by his large shiny forelock. Rock was not in the original Metropolis manga, but he's a significant character in an animated version made after Tezuka's death.
Duke Red: Charming and intelligent, Red originally appeared as a master criminal who mocked the bumbling police in Metropolis. He later appeared in a variety of roles, good and bad, but never lost his suave dignity. His large beak-like nose and hair that sweeps up in back gives him the appearance of a human cockatoo.
Saruta: Recognizable by his large warty nose - his name is taken from the long-nosed god of the tengu.
Saruta inevitably leads a hard life, and is toughened by it; he seems to be always struggling against something. He appears in several volumes of Phoenix, and an elderly version Saruta was Black Jack's mentor.
The gourd: A little doodle with an upside-down gourd for a head, a piglike nose, covered with patches. Gourds are not s much a recurring character as a recurring joke; when Tezuka felt things were too serious, he'd throw in a gourd at an inappropriate moment, or have a bunch of them rain from the sky and bounce of the hero's head.
Other characters listed as "guests" in an Astro Boy issue guide include Ampera, Dr. Fula, Kim Sankaku, Mason, and Skunk Kusai, but I am not familiar enough with these characters to describe them adequately here.