Courtesy Wikipedia:
The Blonde Phantom (Louise Grant Mason) is a fictional masked crime fighter appearing in American comic books published by Marvel Comics. Created for Marvel predecessor Timely Comics by Stan Lee and Syd Shores, the character first appeared in All Select Comics #11 (cover-dated Fall 1946), during the 1940s period fans and historians call the Golden Age of Comic Books. The heroine was so well received that the next issue was retitled The Blonde Phantom. The series continued to feature her until issue #22 (March 1949). She also appeared in backup stories in many other Timely comics; in Superhero Comics of the Golden Age, Mike Benton observes that "for a few months in 1948, readers could find her in seven titles on the newsstand."
Louise Grant is a secretary at the Mark Mason Detective Agency, and secretly in love with her boss. When he is on a case, Louise takes off her glasses and lets her hair down, becoming the glamorous masked hero, rescuing him from danger in a floor-length evening gown.
In a gender reverse to the famous Superman/Lois Lane dynamic, Mark is in love with the Blonde Phantom, and has no interest in the mousy secretary back at the office.
Louise Mason returned in Modern Age comics as a sidekick for The Sensational She-Hulk, from 1989 to 1994.
