As Superboy, Kal-El is the first of Earth's superheroes. Despite the occasional appearance of heroes like Aquaboy and the Japanese hero Sunburst, Superboy is the only superhero who has a well-known public profile until after he becomes Superman. Superboy's solitary status is reduced somewhat when he is reunited with Krypto, infant Kal-El's pet dog on Krypton. Krypto joins Superboy in many of his subsequent adventures as his canine partner, and also has many adventures of his own. Through his discovery of the Phantom Zone, Superboy later finds out he is not the lone humanoid survivor of Krypton.