In a republic, the head of state is typically referred to as a president. This individual may be elected or appointed, depending on the country's specific system of governance.
In a monarchy, the head of state is usually a king or queen. However, in some constitutional monarchies, the head of state may also be a ceremonial figure while the actual governance is conducted by elected officials, often with a prime minister as the head of government. In such cases, other titles like "emperor" or "monarch" might also be used, depending on the specific type of monarchy.