Eudaimonia (Greek: εὐδαιμονία [eu̯dai̯moníaː]; sometimes anglicized as eudaemonia or eudemonia, ) is a Greek word literally translating to the state or condition of 'good spirit', and which is commonly translated as 'happiness' or 'welfare'.

In works of Aristotle, eudaimonia was the term for the highest human good in older Greek tradition. It is the aim of practical philosophy-prudence, including ethics and political philosophy, to consider and experience what this state really is, and how it can be achieved. It is thus a central concept in Aristotelian ethics and subsequent Hellenistic philosophy, along with the terms aretē (most often translated as 'virtue' or 'excellence') and phronesis ('practical or ethical wisdom').

Discussion of the links between ēthikē aretē (virtue of character) and eudaimonia (happiness) is one of the central concerns of ancient ethics, and a subject of much disagreement. As a result, there are many varieties of eudaimonism.