Western science fiction films serve as a battleground for competing discourses on the posthuman body. The imagination of the posthuman body reflects the philosophical debates surrounding the essence of human being in the technological context. Within these debates，transhumanism，extending the humanist tradition，envisions posthuman cyborgs as embodiments of a liberated subjectivity，seeking to enhance human agency and will through technology. Moreover，critical posthumanism advocates for a decentralized culture that challenges anthropocentric views of the body. Therefore，the body narratives in Western posthuman science fiction films portray both the utopian vision of a technologically enhanced future，where technology merges with organic life，and the dystopian fear of the loss of Enlightenment humanism，as manifested in grotesque and uncontrollable body images resulting from technological corruption. Meanwhile，the plasticity of posthuman bodies challenges the essentialist assumptions of human identity，thereby deconstructing traditional biopolitical categories such as gender and race.

posthumanism  /  transhumanism  /  cyborg  /  body narrative  /  agency  /  fluidity