Representations of gender and sexual identity in The Last Man reflect fundamental ambiguities, some of which are the conventional ambiguities of the literature of sensibility.
A "woman's heart and sensibility" and even "woman's work" are defined in the early chapters especially as tied to deep feeling (I.7, II.1, II.2). But both Lionel and Adrian are described as "effeminate" (e.g., III.6--though Lionel says there that "a man must repress such girlish ecstacies") and instances of cross-dressing, homosocial and homoerotic feeling (e.g., I.2), and the sense that gender and sexual identity, like other roles, are performed runs throughout this highly theatrical novel.
In Volume III, chapter 5, a child is assigned shifting pronouns--male, female, and even the neuter "it"--an authorial or editorial mistake, clearly, but one that it has been argued may unconsciously reflect the book's deeper gender ambiguities.
When it comes to female figures from mythology, the novel opens with a Sybil (who may be a type of Cassandra) and contains important evocations of Pandora and Ariadne, as well as the modern myth of Corinne, to name a few, all potentially significant for any reading of representations of gender in The Last Man.