Which superhero's secret identity is Diana Prince?

The superhero whose secret identity is Diana Prince is Wonder Woman. Diana Prince is the civilian identity used by Diana of Themyscira when she operates in the human world.

In Wonder Woman’s original Golden Age stories, Diana adopted the identity from a real woman named Diana Prince. The woman wanted money to join her fiancé overseas, while Wonder Woman needed credentials and a job so she could remain near the injured Steve Trevor. Diana used the identity while working as a military nurse and later in other civilian and government roles.

The alias allowed Wonder Woman to move through ordinary society without immediately revealing that she was an Amazon princess and powerful superhero. Over the decades, different DC continuities have revised how Diana acquired or used the identity. Some versions portray Diana Prince as a constructed cover identity, while others return to the idea of Diana taking the name from another person.

Diana Prince is not Wonder Woman’s birth name in the usual sense. Her royal identity is Diana of Themyscira, and “Wonder Woman” is her heroic title. Themyscira is her Amazon homeland, while Diana Prince is the name most associated with her life outside it.