Julia Kristina Nyberg (née Svärdström; 17 November 1784 – 16 April 1854), was a Swedishpoet and songwriter. Nyberg grew up as the adoptive daughter of a mill owner, named Adlerwald, in the parish of Skultuna in Västmanland County. She wrote the vast majority of her works under the pseudonym Euphrosyne.
Nyberg is most famous for her songs written for the Walpurgis Night holiday, many of which are still sung and recorded today, including Vårvindar friska and Fruktmånglerskan med tapperhetsmedalj. For the majority of her literary career she belonged to the circle of writers based around the Romantic poet Per Daniel Amadeus Atterbom and regularly published her poetry in the group's journal: Poetisk kalender. She never aspired to the epic poetry that characterized many of her contemporaries' works, but instead focussed on writing shorter poems inspired by nature.