Technically, the character who would later be known as "Madame Masque"-- or even just "Masque" in one incarnation-- was called both by her given name "Whitney Frost" and by her formal name as head of the criminal "Maggia," "the Big M." (No relation to "M-Appeal," I guess.)
Whitney Frost, later revealed to be the daughter of the Maggia's former leader Count Nefaria, debuted in TALES OF SUSPENSE #98, as a glamor-girl who began romancing SHIELD agent Jasper Sitwell. The romance was at least partly for show, for she was trying to get intel from Sitwell so that her gang could break into Stark Industries and rip off the inventor's store of super-weapons. (Today, no one would believe that a criminal gang would bother making such a blatant assault, since it would be so much easier to bribe employees into copying the tech-- which more or less became the subject of the "Armor Wars" arc in the IRON MAN title.)
Sitwell only pretended to be fooled by Whitney's blandishments in order to lure her into a trap. Like many sentimental Marvel females, she couldn't resist saving Sitwell's life despite him setting her up to take a fall. Then she escaped. Several issues later, after TALES OF SUSPENSE had morphed into IRON MAN, writer Archie Goodwin essentially ripped off the origin of Doctor Doom, having Whitney facially injured in a tragic accident that forced her to wear a mask to conceal her ruined beauty.
I know that I've said this before of other characters, but from what I've seen of Masque's later incarnations, she never seemed to catch fire outside of the original arc of Goodwin-scripted stories. Goodwin's scripts had a more hard-edged, noir-ish feel than those of Smilin' Stan or any of the many Marvel raconteurs who followed some if not all aspects of Stan's writing-style. Madama Masque, who was a "tough girl" at least a year before Marvel's Black Widow showed any propensity at hand-to-hand fighting, just didn't fit the rather "soft," soap-operatic style of later IRON MAN writers, particularly Bill Mantlo, who tried to make her into Stark's regular girlfriend.