Ulla was born in the undersea continent of Atlantis to a mermaid mother from Tritonis and a legged father from Poseidonis. A mutant, Ulla could change her legs to a fish tail and fly above the water, but could only survive underwater for thirty hours at a time. Due to this limitation, Ulla was raised on land in Denmark by her adoptive parents.
Ulla served as the Danish representative in the Global Guardians for quite some time, being an original member. When the Global Guardians were disbanded by the United Nations, Ulla was brainwashed along with several other Guardian members by the Queen Bee of Bialya. Resisting brainwashing on several occasions, Ulla would be a constant worry to the Queen Bee and her cohorts, fellow Guardian members Owl-Woman and Jack O'Lantern. During that time, Ulla was seemingly killed by the second Jack O'Lantern; however, she turned up later fighting with the Guardians again, stating that is was her "evil" twin who had died. A statue was resuurected along with the other fallen Guardians. This other Little Mermaid may have been the one to join the International Ultramarine Corps.
Sometime much later, Ulla's name as the Little Mermaid would be used by another young woman with similar powers. This new Little Mermaid would join the International Ultramarine Corps, associated with such heroes as Vixen. Her origins and exact ties to Denmark or the original Little Mermaid are unknown.
Born in the undersea continent of Atlantis to a mermaid mother from Tritonis and a legged father from Poseidonis, Ulla would manifest different abilities than her kin. A mutant, Ulla could change her legs to a fish tail and fly above the water, but could only survive underwater for thirty hours at a time before needing to return to the surface. Ulla is a powerful swimmer and could cross vast distances of body's of water without tiring for quite some time. Her strength, stamina, and vision are also heightened to be able to deal with the pressure of being underwater.