The King of The Copper Mountains is a children's novel by Paul Biegel, and was originally published as Het Sleutelkruid in the Netherlands in 1964, where it won the Gouden Griffel, the award for the best children's book of the year. An English translation by the author with illustrations by Gilliam Hume was published in 1968 by J. M. Dent. It was reprinted by Franklin Watts in 1969, by Collins Armada in 1971, 1973 and 1989, and by Fontana Lions in 1980 and 1987. The book was also translated into German, Afrikaans, Danish, and Spanish.