Human enhancement technologies offer prospects for improving the mental capacities that are typically considered to ground moral status. Bioethicists, posthumanists and transhumanists have raised the worry that the radical enhancement of our moral status-relevant capacities is open to the possibility of creating supra-persons. The worry is that supra-persons would further reduce the moral inviolability of mere persons. If the possibility is plausible, then radical enhancement would put mere persons at risk. In order to assess the plausibility of possibility claims, epistemologists (...) have investigated the role of imagination in justifying our beliefs about what is possible. Philosophy has abounded with imaginability arguments for various entities like zombies, experience machines, super-spartans, and perfect actors. The aim of this paper is to investigate a newcomer in the bestiary of bioethics, the supra-person, using the utensils of imaginability-based modal epistemology. We will argue for an epistemic claim: that no imaginative act is sufficient to justify the belief that supra-persons are possible. In order to support our thesis, we will employ two influential accounts of the relation between imaginative acts and acquiring justification for beliefs about what is possible. (shrink)