Wonder Woman is a fictional superhero created by American psychologist and writer William Moulton Marston. She first appeared in All Star Comics #8 in December 1941 and has since become one of the most iconic and powerful female superheroes in the world. The term 'Wonder Woman Is One' refers to her being the first female superhero in comic books. The crossword solution for this term is 'AMAZON', which is a reference to the mythical race of female warriors from Greek mythology.