This thesis reads British Boom science fiction and critical posthumanism as a proliferation of story engines, which are sites of ideation where the boundaries between disciplinary sites of meaning-making and world-forming are reconfigured and unsettled. Five exemplary writers of the post-1990s British Boom science fiction period – Matthew De Abaitua, Alastair Reynolds, Jeff Noon, Adam Roberts, and Justina Robson – explore different conceptualizations of the human in the time of the posthuman. For this, the emergence of a posthuman curator is necessary to account for both fiction and theory as entangled agencies, which unsettle normative assumptions about humanity, as the universal measure of things and as dominant species in the time of the Anthropocene. The conceptual argument is simple in its outline: the curator is a performative account of science fiction’s posthumanizing potential, where the curator occupies a diffractive framework (following Karen Barad) unsettling works of science fiction from the sanctity of categorisation and practices that limit its ability to explore that which cannot yet be imagined. The materiality of these texts and the phenomena which they enact – for all matter is enfolded with/in these story engines of British Boom science fiction – explore how the nature of change is changed through these entangled agential forces. These curators unsettle the status of individuals, human or otherwise, machines, animals, and species. This thesis therefore foregrounds the potential of science fiction as the encounter and transformation of humanity into something otherwise than human – the process which Stefan Herbrechter refers to as “posthumanization”.1 As such, other models of life – virtual, technological, animal – inform the tropes, the narrative arcs, and the subject positions possible in posthumanizing narratives.