 Nicolaus Taurellus (b. 1547 Montbéliard, d. 1606 Altdorf) is one of the early modern German philosophers who re-established metaphysics as a topic of serious academic inquiry in the Lutheran tradition. He adhered to the pious goal of providing a unified account of philosophical and theological truth, but in doing so he developed a series of controversial claims, such as the view that the basic constituents of reality are immaterial, form-like entities. In contrast to traditional form-matter composites, he maintained that such form-like entities fulfill the criterion of substantiality—the capacity of subsisting independently of other entities. At the same time, he held that the composition of immaterial entities can form only accidental, non-substantial unities. His conclusion that human beings are only accidental, non-substantial unities was perceived as a challenge to traditional views of personhood. During his lifetime, Taurellus’s philosophy met fierce opposition from orthodox Lutheran theologians. Still, his metaphysics prefigures some basic ideas of the metaphysics of Leibniz, who knew Taurellus‘s philosophy and thought highly of it.