There are many bosses in Final Fantasy XV, but the ones that come to mind are the two main antagonists, Noctis and Prompto. They are both incredibly difficult to defeat, and even if you do manage to do so, it’s often not an easy task. Here is a list of the 10 hardest bosses in Final Fantasy XV: 10. The Mad King Cecil The Mad King Cecil is one of the most difficult bosses in Final Fantasy XV. He has a lot of health and attack points, and he can easily kill you with just a few hits. He also has a powerful ability that can easily kill you if used at the right time. If you don’t have any magic or strong attacks, it’s best to stay away from him until he dies.