Andvari is a character from Norse mythology, known as a dwarf who possesses the ability to transform into a fish. He is famous for his magical ring, Andvaranaut, which grants wealth to its owner. However, the ring also brings misfortune, leading to conflict among gods and heroes. In the myths, Andvari is captured by the god Loki and forced to give up his treasure, including the cursed ring. This story highlights themes of greed and the consequences of wealth, as the ring's curse affects many characters, including the hero Sigurd and the dragon Fafnir.