Sex robot scholarship typically focuses on customizable simulacra, lacking sentience and self-awareness but able to simulate and stimulate human affection. This paper argues that future humans will want more: sex robots customized to possess sentience and self-awareness [henceforth, sexbots], capable of mutuality in sexual and intimate relationships. Adopting a transdisciplinary critical methodology focused on the legal, ethical and design implications of sexbots, it assesses implications of sexbots' non-mammalian subjectivity, balancing designed-in autonomy and control, decision-making capacity and consent, sexual preferences and desire, legal and moral status, vulnerability and contrasts between mammalian and non-mammalian moral decision-making. It explores theoretical, ethical, and pragmatic aspects of the tensions involved in creating sentient beings for utilitarian purposes, concluding that sexbots, customized manufactured humanlike entities with the capacity for thought and suffering, have a consequent claim to be considered moral and legal persons, and may become the first conscious robots. Customizing sexbots thus exemplifies many profound ethical, legal and design issues. The contradictions inherent in their inconsistent ethical and legal status as both manufactured things and sentient, self-aware entities who are customized to be our intimate partners augments existing human/animal scholars' call for a new theoretical framework which supersedes current person/thing dichotomies governing human responsibilities to other sentient beings. The paper concludes that the ethical limits and legal implications of customizable humanlike robots must be addressed urgently, proposing a duty on humans as creators to safeguard the interests and minimize the suffering of created sentient beings before technological advances pre-empt this possibility.