Kostas Krystallis (Greek: Κώστας Κρυστάλλης; 1868–1894) was a Greek author and poet, representative of 19th century Greek pastoral literature. He was born an Ottoman subject in Epirus, but escaped to Greece after being denounced to the authorities for writing a patriotic collection of poetry. Krystallis initially wrote his works in archaic language, but after 1891 he adopted the vernacular (Demotic) Greek language and became influenced by the New Athenian school. He was a pictorial writer, with a love of nature, while most of his work was based on traditional folk poetry.

Kostas Krystallis, was born in the village of Syrrako, Epirus, then Ottoman Empire. He was the son of a local merchant. When his mother died he moved together with his father to Ioannina, where he attended the Zosimaia High School. As a pupil he wrote his first poetry collection, named Σκιαί του Άδου ("Shadows of Hades"), which consisted of three short stories, and exhibited obvious borrowings from Dante's Inferno and Homer's Odyssey.[4] Because of this highly patriotic work he was denounced by the Ottoman authorities, and sentenced to 25 years in exile. Krystallis managed to escape to Greece at 1886.

While living in Athens he changed several jobs: initially worked as a typographer, copy editor and author in an encyclopedia, secretary for the periodical Η Εβδομάς ("The Week") and then ticket inspector in the national railway. For a short period he became author in the newspaper Φωνή της Ηπείρου (Voice of Epirus) and supported the rights of the population of his home place Epirus, which was still under Ottoman control. At 1893, he lost his job; however, he won a lottery prize and could so afford the publication of a number of works he composed that time. Krystallis died of tuberculosis on April 22, 1894, aged 26.