"Nøkken" - Theodor Kittelsen, 1892
Nøkken is pronounced "Nuck-en". Ø is pronounced like the U in "shut".
The word "Nøkken"
Nøkken is known by several different names. In southeastern and northern Norway he's known as Nøkken, in western Norway and parts of Telemark he's known as Nykkjen, and in Sweden he's known as Näcken, sometimes spelled Necken. All of these words evolved from the Old Norse word "nykr". Because Nøkken is rarely ever mentioned in Norse mythology, it's a bit unclear what exactly nykr means, but it seems closely related to other Germanic words at the time, such as the Old English word