The Women of Gormenghast
I think I've made it clear that I'm something of a fan of Peake's work. However, it has to be said: his depiction of female characters is…pretty bad. His men can be good or evil or just buffoons--they can be anything. Whereas virtually all of his women are either A) tragic victims; or B) pitiable grotesques. The only significant exception to this rule is the Countess, Titus' mother. She's an interesting, nuanced character with agency. But as for everyone else…well, just look:
(oh yeah, SPOILERS in what follows)
Fuchsia--Hey, did you know there's a Strawbs song about Titus' sister? You can see Tolkien's influence in a LOT of music of a certain type, but to my knowledge (imperfect, admittedly), this is the world's only Peake song. But really: in spite of a promising initial appearance, Fuchsia is quickly reduced to the level of victim--victim of the castle's inertia, victim of Steerpike--and her Ophelia-like end is mainly meaningful for how it effects other people. The idea that she was inevitably doomed doesn't really pass muster, given that Titus himself isn't. WHAT POSSIBLE DIFFERENCE COULD THERE BE BETWEEN THE TWO?!?
Cora & Clarice--The earl's half-witted sisters are sheer grotesques, with no agency of their own.
Nanny Slagg--The nursemaid of the royal children is self-pitying, none too bright, and once again without agency.
Keda--Titus' wetnurse's story takes up a somewhat baffling amount of space in Titus Groan, though this does pay off in Gormenghast (though none too satisfactorily; see below). Even more than Fuchsia's death, her suicide seems quite unjustified as anything but an aesthetic spectacle, and one gets the unavoidable impression that it happens mainly because she's a woman.
Irma Prunesquallor--The doctor's sister while unmarried is a pathetic and dimwitted spinster; once she marries, she morphs into a cartoon of marital strife in the Maggie & Jiggs mold.
"The Thing"--Keda's feral daughter is just the fucking worst. The first clue might be that she's only ever referred to as "the Thing," but it's much worse than that: the only purpose she serves is to allow Titus to Come Of Age; after that--I mean, like, literally, within a few sentences of that--Peake kills her off in a ludicrously convenient, perfunctory way that would be funny if not so insulting. This is the worst part of Gormenghast by a wide measure.
Black Rose--A perfect distillation of the victim thing: she's barely a character; she appears, she was abused, she dies, boom.
Juno--Actually, it's conceivable that she could be another exception, were she better developed, but she suffers from the thinness that afflicts most of Titus Alone, so it's hard to say what to make of her.
Cheeta--Another possible exception, but given that her role is to be spurned by Titus and thus plot an absurdly over-the-top revenge scheme…I wouldn't exactly call it an improvement.
I should note that these are not all bad, in themselves; in particular, Cora and Clarice have a quite queasily effective trajectory. It's just that this is all there is, you know? Very few counterexamples.