- Real Name: Unknown
- Alias: Dolphin
- Identity: Secret
- Alignment: Good
- Gender: Female
- Hair: Silver, Eyes: Blue
- Occupation: Adventurer
- First appearance: Showcase #79 (December, 1968)
- Appearance of Death: Infinite Crisis #3 (February, 2006)
Dolphin is the sole surviving member of an alien experiment on Humans. She was freed by the spirit of Kordax the Cursed, from Atlantis' early days, then found by Navy officer Chris Landau and his crew. She was initially an attraction at Oceanworld but eventually returned to the sea. Like the mammal she's named after, her mind is of the moment, with little memory, and she did not recall Landau when they met later again. Instead, she found Atlantis and was welcomed by its people. Once there she initially flirted with Aquaman himself, but fell in love with his adopted son, Tempest. She joined the two on several journeys until she and Tempest married. They had a child, during the war between Atlantis and Cerdia. The baby was named "Cerdian" to help heal the conflict. Dolphin insisted that Tempest give up his work with the Teen Titans to devote his time to their family.
Sadly, Garth's retirement did not bring the tranquility Dolphin had hoped for. During the Infinte Crisis, the Spectre, who had been driven unstable without a human host and on a rampage against magic, homed in on the strong magical energy of Atlantis, and destroyed the city. Garth later turned up, unable to properly breathe underwater, and without any idea on where Dolphin and Cerdian were.