It often seems as though older women in fantasy stories and, particularly, western fairy tales, fit into one of two character types: either the fairy godmother (for example in Cinderella and too many other examples to list) or the evil witch (such as in Sleeping Beauty, where the wicked fairy takes on the appearance of an old woman, spinning). There seems to have been an assumption over the ages that when a woman becomes old, she also gains wisdom. This has been warped into the character of the evil, ugly witch. For example, Baba Yaga, the witch in Russian folklore, is predatory in some stories but in others, she is a helper. But, in spite of her powers, she is always described as hideous.
Older women are often depicted as grandmothers, white haired, bent and ancient, even though many of today’s grandmothers (and I should know, I’m one) are (we hope) nowhere near their twilight years. This character archetype is often not a proactive one. In Red Riding Hood, Granny is bedridden and frail and the wolf uses her to deceive and entrap the heroine. In the original version by Perrault she dies. In other versions, for example by the Brothers Grimm, a woodman kills the wolf and cuts Red and Grandma, alive, from its stomach. It’s refreshing to find an empowered (although younger) female in James Thurber’s 1939 parody of this story in Fables For Our Times, in which Red Riding Hood shoots the wolf-as-Grandma (with the moral ‘It is not so easy to fool little girls nowadays as it used to be’). Dahl also parodied it in Revolting Rhymes (see above link).
Sometime older women characters are called Granny even when they’re not, such as Terry Pratchett’s hard-headed, stern, but infinitely wise witch Granny Weatherwax, who is in fact unmarried and childless. Her place is one of the respected and admired older woman. Other witches in his books have honorific titles like Old Mother, Nanny, and Goody.
There are others in Pratchett’s works besides the witches. They usually appear in the more stand alone stories, like Reaper Man which has a feisty old lady, and there are the heads of the Seamstresses (for which those unfamiliar with the great Sir Terry should read prostitutes) Guild and of the Beggars Guild. In his Watch series, there’s Lady Sybil, not in her twenties when she first appears, who has carved out a career breeding dragons and who marries the anti-hero. He falls for her; she doesn’t set out to “catch him”.
Actually, I think having a main character that is “older”, however you might define it, is rare, whether they’re male or female. I deliberately tried to go against that when I started writing my stories about two older ghost busters. You can find some of them here. It all started with a “boy fancies girl next door” theme, but they both were aged in their early sixties. Now, though, I realize I’m the age they were at the start of the series, and if anyone calls me elderly I’ll turn them into a frog.