Regicide is the killing of a king, which has been a crime throughout history. It is considered a serious offense and is punishable by death in many countries. Regicide is often seen as a form of treason, as it is an attack on the state and its leader. In some cases, it is seen as a form of justice, such as when a tyrant is overthrown. Regicide has been used as a political tool throughout history, with some rulers being killed to gain power or to prevent them from taking power.