Kim Novak tended to specialize in the objectified woman role, where the character's arc was more about mirroring the leading man's desires than any self-determination. This is true of at least 4 films featured in The Kim Novak Collection: Picnic (1955) has her casting off the constraints of being the hometown beauty queen to live a life of vagrancy with William Holden's former star athlete turned shiftless loser. In Bell, Book and Candle (1958), she's a witch who's willing to lose her supernatural powers for the love of a good man played by Jimmy Stewart. Having been cruelly mistreated in a former marriage, she falls for the much older Fredric March as a substitute father figure in Middle of the Night (1959). And although Frank Sinatra's philanderer makes no promises in Pal Joey (1957), she's just sure that he'll get used to the idea of fidelity. The one exception here is as the titular character and real-life actress in Jeanne Eagels (1957), who's willing to use anyone to become a star. Eagels castrates the men in her life as she rises to the top, but because her narcissism is so thoroughly rebuked (showing her drug addiction, alcoholism, malaise and early demise), the film reassures Novak's other characters that they made the right choice. For a proper critique of the beautiful feminine spectacle, of course, we have Vertigo (1958).
[W]ith her head of writhing snakes, huge mouth, lolling tongue and boar’s tusks, the Medusa is also regarded by historians of myth as a particularly nasty version of the vagina dentata.
-- Barbara Creed, The Monstrous-Feminine: Film, Feminism, Psychoanalysis
More to the point of this post, Alfred Hitchcock demonstrated along with Creed's Medusa that hair can be really frightening, and nowhere is this more evident than in the coiffures forced upon Novak. Her stylists had one of two choices: go with the short hair she wore outside of the movies, or give her attachments. These mudflaps made for the worst hairstyles seen on a woman in film since Jean Harlow. And, as was the case with Harlow, we're supposed to think of glamor, rather than trailer park. Hitchcock played the shorter, urbane style against the terrifying mullet (Madelaine the ideal versus Judy the something to work with), but in Picnic we're supposed to think of the above as luxurious. As Novak explains in an extra, she doesn't have thick hair, so she tended to trim the add-ons to fit her hair better. That plan didn't work so well when her extensions were supposed to be cascading out of the window. On the other hand, the styled version wasn't much better:
It's too close to this monstrosity. And was Jeanne Eagels' knotted mullet really a style back in 1910?
I like the cut in Bell, Book and Candle; it goes well with capri pants. But someone decided to give her a brown wash, which looks like she spent too long in the swimming pool:
Which thankfully doesn't so much matter in black and white:
And, finally, she was given a faux-hawk for Pal Joey: