As is well known among jurists, law has a special conception of personhood: corporations are persons, whereas slaves have traditionally been considered property – ‘things’ – rather than persons. This peculiar state of affairs has not garnered the interest of legal theorists for a while; the theory of legal personhood has been a relatively marginal topic in jurisprudence for at least 50 years. However, many recent developments call for a theoretical investigation of this topic. Animal rights activists have been demanding that certain animals be recognised as legal persons in various countries. In some US states, so-called foetal personhood amendments – redefining foetuses as legal persons for some limited purposes – have been proposed and passed. Moreover, technological progress heralds brand new conundrums: Could and should autonomous artificial agents be endowed with legal personhood? How should we relate to the prospect that interspecies – including human–animal – biological mixtures could be created in the future? All this demands not only adopting appropriate regulative measures but also a serious reconsideration of the philosophical underpinnings of the legal conceptions of personhood. The contributors of this book analyse and explain these recent developments.