Scholars have often underlined the influence of medieval theological voluntarism in Thomas Hobbes’ thought. The article aims to identify the similarities with some theses of medieval ethical voluntarism in Thomas Hobbes’ Leviathan. The evolution of the concept of good is considered starting with the ethical thought of John Duns Scotus and William of Ockham. The concept of good understood as individual advantage and self-preservation comes to Hobbes probably through Scotus’ influence in Francisco Suárez. In addition, the approaches to moral obligation and to good and evil seem to be the Ockham’s legacy to the Hobbesian moral and political thought.