Peter Nansen (20 January 1861 – 31 July 1918) was a Danish novelist, journalist, and publisher.

He is best known as the author of the novels Julie's Diary, Marie, and God's Peace, which together constitute Love's Trilogy.

[1] Marie in particular became in short order very highly esteemed, and Pierre Bonnard's illustrations (which appeared in 1897 in La Revue Blanche) for the novel were much admired by Renoir.

Nansen was born in Copenhagen and worked for two decades for the publishing house Gyldendal.

[3] It was in his capacity as an editor at Gyldendal that he famously told Sigrid Undset not to attempt to write any more historical novels because she had "no talent for it.