Astro is a Robot Kid created as a Replacement Goldfish son by Dr. Umataro Tenma after his young son Tobio is killed in an accident. Though Astro is a robot, he wants to blend in with humans. Astro has amazing powers, including Super Strength and Flight, and regularly fights crime, including his antagonistic father Dr. Tenma and various other robots. Astro is adopted by the kindly Professor Ochanomizu after Tenma abandons Astro for not being a perfect clone of Tobio. Astro also has a large family of other robots, including his younger sister Uran.
Many of Astro's expies follow his basic character in one form or another. They'll be young-seeming humanoid (usually ridiculously human) robots, often developed as Replacement Goldfishes. They are usually given Super Strength and flight (or at least hovering) abilities. It's not uncommon for them to have Pinocchio Syndrome and want to Become a Real Boy. Astro Clones are often created by a skinny Tenma-looking scientist or a rotound Ochanomizu-looking one. When it comes to designs, they're usually white-and-blue or black-and-blue, with pointy Anime Hair.
- Concrete Revolutio: Choujin Gensou: Among the many Retraux Expies filling out the cast, Earth-chan is a Composite Character of Astro and the Sputnik satellite - a super-powerful Robot Girl who lives in orbit, and can appear instantly in response to the cries of people in suffering. While she starts off as possibly the most admired hero in the setting, her nature as both a child and a robot causes her to see everything in black-and-white; she can't understand why humans tell lies, nor predict long-term consequences of her actions, which clashes horribly with the complex politics of post-war Japan. When on one occasion she gains the ability to dream, she sees herself as a human with a loving family.
- Jetter Mars is a series by Osamu Tezuka that stars an Expy of Astro, which Osamu Tezuka also created. It was originally intended as a remake of the original Astro Boy anime, but a Troubled Production led to Tezuka creating Jetter Mars instead. Jetter is similar looking to Astro, but he has a more bratty personality like Uran. Various other characters have expies as well (Miri to Uran, Dr. Yamanoue to Dr. Tenma, etc).
- Beyblade V-Force features Zeo, a villainous example of this trope. He was built by doctor Zagāto to replace his dead son, but he doesn't know it until his father tells him so, and instructs him to get the main characters' four Bit Beasts in order to Become a Real Boy with their power. (In the manga, his situation was a bit different: the current Zeo is not a robot replica of the original one, but his younger brother who got brainwashed by his father to believe he's Zeo)
- Obotchaman AKA Caramelman #004 from Doctor Slump is visually very similar to Astro, anime hair included, and like him he's very kind and polite to everyone. The only major difference is that his creator is a Mad Scientist and the closest thing the series has to a Big Bad.
- Rusty from The Big Guy and Rusty the Boy Robot (and its animated adaptation) references Astro. He's a young Robot Kid inspired by Astro, albeit with a red color scheme.
- An issue of The Simpsons discusses the idea of rebooting Poochie and "Astro-Poochie" is one of the suggestions.
- Astro Boy makes a Lawyer-Friendly Cameo standing in the background with the Pink Child in the final issue of The League of Extraordinary Gentlemen.
- The rewrite RWBY: Scars adds onto what Astro Clone traits Penny has in canon. Penny Polendina is a Flying Brick Robot Girl who wants to be seen as human. She has two father figures, her creator Pietro Polendina and James Ironwood. It's later shown that Ironwood is literally Penny's dad. Penny is the Replacement Goldfish for Ironwood's Ill Girl daughter Penelope Ironwood, who had her soul transferred into a robot. Penny, however, only has brief memories of her past life and has an existential Heroic BSoD upon being told the truth.
- Ambertwo from Pokémon: The Birth of Mewtwo (and its Animated Adaptation in Pokémon: The First Movie) is a clone of a deceased child named Amber. Amber's scientist father decided to clone Amber, but his Replacement Goldfish failed when Amber's clone died before she could wake up. Amber's father, Professor Fuji, has a design based off of Tenma. Unlike most Astro Clones, Ambertwo was an ordinary human, aside from being a clone.
- As Mega Man was originally going to be a Licensed Game of Astro Boy before Capcom lost the license to use Tezuka's characters, the eponymous hero's original design and powers are deliberately based off of Astro, with the only differences being his mostly-blue color scheme, his Arm Cannon, and his iconic blue helmet. His creator Dr. Light is also inspired by the kindly Professor Ochanomizu in both design and personality, while his "sister" Roll is based on Uran. Big Bad Dr. Wily in turn resembles Dr. Tenma, but only in terms of the latter's antagonistic role.
- Tekken: Alisa Bosconovitch is a robot duplicate of Dr. Bosconovitch's deceased daughter, originally designed to serve and protect Jin Kazama and is usually seen with Lars Alexandersson. She is seen by one part of the cast as nothing but an expendable tool while the other sees her as an actual person. She fights using several weapons such as chainsaws, rocket fists, and her head that also functions as a bomb.
- Super Knockoff VS is based entirely around expies, as the name suggests. With Cosmo Kid filling this trope. At least originally, before becoming the game's jealous glitch-powered Big Bad.
- Jenny from My Life as a Teenage Robot is a superpowered Robot Girl who just wants to be a normal human teen. Her mother has a design similar to Dr. Tenma, but she's a benevolent parent (besides her being unsupportive of Jenny's "human name" and her Pinocchio Syndrome). Jenny has a blue-and-white scheme with pointy Girlish Pigtails, similar to Astro's pointy Robot Hair.
- OK K.O.! Let's Be Heroes: "Sidekick Scouts" introduces Combo Breaker, a blatant parody of Astro Boy. He's a cyborg boy built by a scientist who resembles Dr. Elefun, he's got Astro's pointed hairstyle, his usual outfit is a pair of briefs painted onto his body, and he's got all sorts of gadgets like rocket boots and butt-mounted laser guns build into his body. Though his personality is an exaggerated version of KO's "cutesy, clumsy-yet-enthusiastic helper" shtick, to serve as a foil when he decides he wants to be KO's sidekick.
- Robotboy of Robotboy is based off of Astro. Robotboy was created by a Japanese professor, Professor Moshimo, with the most advanced fighting capabilities on the planet, but the mind of an 11-year old boy. To keep him out of the wrong hands, Robotboy is sent to live with an American boy named Tommy Turnbull, who teaches Robotboy to be like a human boy. Robotboy is a Pint-Sized Powerhouse and a Flying Brick who is later given an Uran-like Distaff Counterpart in Robotgirl and is also shown to have an older evil counterpart named Protoboy.
- The Venture Bros. has a cruel twist on this with Ro-Boy, who's one of the former boy adventurers in therapy with Dr. Venture in the episode "Self-Medication".
- Rikki Roundhouse in the Duck Dodgers episode "The Menace of Maninsuit". We don't learn much about his backstory, but visually he looks almost exactly like Astro Boy, only with a yellow-and-black colour-scheme and a fin on his head.
- Hero Boy, a Show Within a Show from Freakazoid!. His Catchphrase is "I must succeed!", but he never seems to succeed, though. The one episode we see has him trying to fight a giant robot, and doesn't make so much as a dent.
- DuckTales (2017): B.O.Y.D.'s backstory (as detailed in the episode "Astro B.O.Y.D.!") contains multiple homages to the franchise:
- B.O.Y.D.'s original name in the episode was 2BO. Astro/Atom was made to replace Dr. Tenma's dead son Tobio.
- Dr. Akita dresses like Dr. Tenma, including the labcoat and sunglasses.
- The detective who stopped his original rampage is named "Tezuka", after Astro Boy creator Osamu Tezuka.
- B.O.Y.D. eventually learns he can fly with feet that turn into rockets.
- A diagram of B.O.Y.D.'s insides show a part with Heart Symbol, a recurring element of the franchise that was especially prominent in the 2003 anime.
- B.O.Y.D. turns out to be a benevolent creation of Gyro's that Dr. Akita repurposed as a weapon, essentially a reverse of Astro Boy's origin (where he started out as a weapon project that was repurposed to be Tenma's Replacement Goldfish).
- The Couch Gag at the start of The Simpsons episode, Tis The Fifteenth Season has the family as anime characters with Bart as Astro Boy.