King Frederick William Koko, Mingi VIII of Nembe (1853–1898), known as King Koko and King William Koko, was an African ruler of the Nembe Kingdom (also known as Nembe-Brass) in the Niger Delta, now part of southern Nigeria.
A Christian when chosen as king of Nembe in 1889, Koko's attack on a Royal Niger Company trading post in January 1895 led to a retaliatory raid by the British in which his capital was sacked. Following a report on the Nembe uprising by Sir John Kirk which was published in March 1896, finding that forty-three of Koko's hostages had been murdered and ceremoniously eaten, Koko was offered a settlement of his grievances but found the terms unacceptable, so was deposed by the British. He died in exile in 1898.
King Koko of Fantippo, a character in the Doctor Dolittle books of Hugh Lofting (1886–1947), appears to be based on the real King Koko.