Krypto was the only white dog born in a litter of three in the wake of Doomsday's rampage through Metropolis. His owner, an aging homeless woman from Suicide Slum, found that she could not feed the poor puppies and decided to send them to a better place. Rather than watch them suffer, she wrapped them in a tarp and dumped the litter in Metropolis Bay. Fortunately, a kind-hearted man named Bibbo Bibbowski witnessed the event and bravely dove into the bay to rescue the dogs. Of the three, only Krypto survived. Bibbo decided to adopt the pooch and named him after his favorite superhero's home planet – Krypton.
Bibbo contracted a man to make a special dog-tag collar for Krypton, but the man who made the tags had a strict "six letter only" policy, so the dog's name was shortened to Krypto. Bibbo took care of Krypto for a short while, but he eventually came into the care of Dubbilex at Project Cadmus after the Fall of Metropolis. Bibbo thought that Krypto would be safer away from the city and Dubillex felt that his charge, Superboy, might benefit from having a pet and gave Krypto over to him. However, Superboy despised the dog, and Krypto's feelings towards the Metropolis Kid were equally mutual. As Superboy spent more and more time away from his colleagues at Cadmus, Dubbilex began to take care of Krypto's needs full-time.
Eventually Krypto came under the care of Superboy's old school-friend, Hillary Chang.
Krypto owns a bone-shaped dog collar with his name engraved upon it. On occasion he has been known to sport a dog-sized simulacrum of Superman's cape.
- The original Krypto was created by Otto Binder and Curt Swan in Adventure Comics #210. This version of the animal was created by Karl Kesel and Tom Grummett.
- Unlike previous and posterior incarnations of the character, this version of Krypto does not hail from the planet Krypton. Born on Earth, he is a normal, healthy dog with no powers or super-abilities whatsoever.
- There was more than one homage given to the Silver Age counterpart. In Superboy (Volume 4) #6, for example, Krypto wandered into a fight between Superboy and Parasite and was sent flying through the air with a bit of red cloth (looking like a cape) stuck in his collar.
- 25 Appearances of Krypto the Earth Dog (New Earth)
- 2 Images featuring Krypto the Earth Dog (New Earth)
- Quotations by or about Krypto the Earth Dog (New Earth)
- Character Gallery: Krypto the Earth Dog (New Earth)