The series ran 207 issues from Winter 1945 to December 1973, a 28-year span that included one of the first Marvel Comics annuals (in 1962), and spin-offs including A Date with Millie, Life with Millie, Mad About Millie and Modeling with Millie. Initially a humorous career-gal book about New York City model Millie Collins, it very quickly evolved into a broader, more slapstick comedy — though for a time becoming a romantic adventure series with all the same characters (#113-153, March 1963 - Aug. 1967) before returning to humor.
The premiere issue was penciled and inked by Ruth Atkinson, one of the pioneering women cartoonists in comic books; some sources credit her with creating the character, while others say it was a co-creation with writer and Timely editor-in-chief Stan Lee. Following this first issue, subsequent early stories were drawn mostly by Timely staffer Mike Sekowsky.
The character's essential look, however, was the work of future Archie Comics great Dan DeCarlo, who would later create Josie and the Pussycats and other Archie icons. DeCarlo's remarkable 10-year run one one series, from #18-93 (June 1949 - Nov. 1959), was succeeded by the team of writer Stan Lee, Marvel's editor-in-chief, and artist Stan Goldberg, a.k.a. "Stan G.", the main Atlas/Marvel colorist at the time. Goldberg mimicked the house style DeCarlo set, and later went on to work with him at Archie, as did occasional Millie artist Henry Scarpelli. Al Hartley and Ogden Whitney provided an occasional cover.
The occasional backup feature included a four-page "Powerhouse Pepper" story by famed cartoonist Basil Wolverton in #9, and work by humorist Harvey Kurtzman in #8, 10-11, 13-14, & 16. Lee and Goldberg had Jack Kirby guest-star in a story in #107 (March 1962), though the image itself did not particularly look like the comics legend.
Millie herself became part of the Marvel Universe with Fantastic Four Annual #3 (1965), which chronicled the wedding of Reed Richards and Susan Storm: fellow humor-comic stars Patsy Walker and Hedy Wolfe, among the sidewalk crowd outside, talked about wanting to catch a glimpse of celebrity Millie, whom they'd heard was on the guest list.