First Appearance: Millie the Model #2 (October 1946).
Golden Age Appearance: Millie the Model #2.
Modern Appearance: Marvels #2.
Dates Active: 1946-?
Millie Collins was the eponymous teen model of Millie the Model. In one issue she put on a mask and veil and posed as the "Blonde Phantom" to sell makeup for the General Cosmetics campaign. She did not fight any crimes--that we know of. She also predated the Blonde Phantom (II) by a month or two, and perhaps inspired Louise Grant to put on a costume and fight crime.
JRaghu wrote with some kind words about the site and some information about Millie Collins' modern appearance:
Millie Collins did make a post-Golden age appearance. In issue two of Marvels, she was spotted as one of the guests at the wedding of Reed and Sue Richards (the Luke and Laura of comic books). If I recall, one of the celebrity watchers in the crowd said :"Look - that's Millie Collins the model! My boy has a poster of her!" Now, this prompts the question of why a teenaged boy (and judging from the woman's appearance, I would say that is a fair estimate of his age) living the early-mid 1960s would have a picture of model whose best days were most likely in the 1940s, but I digress. The point is that Millie was there at the wedding.