From 1960 to 1963, Elizabeth II was Queen of Nigeria: Nigeria was an independent constitutional monarchy. She was also the monarch of the other Commonwealth realms, including the United Kingdom.
Nigeria became independent on 1 October 1960 under the Parliament of the United Kingdom's Nigeria Independence Act. The Queen was head of state, though her constitutional roles in Nigeria were mostly delegated to the Governor-General of Nigeria.
The retention of the monarchy was unpopular with Nigerians, and all political parties in Nigeria agreed that the country should be a republic. Nigeria severed its link with the British monarchy, and adopted the President of Nigeria as head of state, on 1 October 1963.
The Queen visited Nigeria twice: 28 January–16 February 1956 and 3–6 December 2003, the latter time to attend the Commonwealth Heads of Government Meeting 2003.