Which nations are run by a prime minister?

Nations that have parliamentary or semi-presidential system of government are run by a Prime Minister.

Countries with Parliamentary systems have a Head of State and a Head of Government. The Parliamentary system may be Constitutional Monarchies like United Kingdom, Sweden, and Japan or Parliamentary Republic like Ireland, Germany, India, and Italy.

Prime Ministers are the Heads of Government whereas Heads of State hold only a ceremonial position with its reserved powers.