The purpose of this thesis is to provide a contrast to the literature on early modern Dutch philosopher Benedictus de Spinoza's notable agreements with Stoic eudaimonism in his ethical framework. I intend to emphasize what is meaningfully non-Stoic in Spinoza's own eudaimonism, while nevertheless granting that there is undeniable conceptual common-ground between them. I seek to illustrate where Spinoza departs from Stoic eudaimonism by outlining his agreements with two philosophers who function as a conceptual contrast to the Stoics: Aristotle and Epicurus. This thesis, in turn, lays out Aristotle, Epicurus, and Spinoza's respective views on the ontological and ethical (that is eudaimonistic) nature of pleasure. All three philosophers are committed to two fundamental claims that are strongly antithetical to the Stoic view of pleasure: (a) pleasure holds a necessary connection to the health of one's state of being and (b) pleasure is by nature good.