Gunnar Gunnarsson (18 May 1889 – 21 November 1975) was an Icelandic author who wrote mainly in Danish. He grew up, in considerable poverty, on Valþjófsstaður in Fljótsdalur valley and on Ljótsstaðir in Vopnafjörður. Despite great difficulties, he became one of the most popular novelists in Denmark and Germany.

Often considered one of the most important Icelandic writers, he wrote the novel Af Borgslægtens Historie (translated into English as Guest the One-Eyed), the first Icelandic writing ever made into a movie. He also wrote the autobiographical novel The Church on the Mountain (1923–28).