Johan Ludvig Heiberg (27 November 1854 – 4 January 1928) was a Danish philologist and historian. He is best known for his discovery of previously unknown texts in the Archimedes Palimpsest, and for his edition of Euclid's Elements that T. L. Heath translated into English. He also published an edition of Ptolemy's Almagest.
Heiberg was born in Aalborg, the son of Johanne Henriette Jacoba (née Schmidt) and Emil Theodor Heiberg. Heiberg was Professor of Classical Philology at the University of Copenhagen from 1896 until 1924. Among his more than 200 publications were editions of the works of Archimedes (1880 and 1912), Euclid (with Heinrich Menge) (1883–1916), Apollonius of Perga (1891–93), Serenus of Antinouplis (1896), Ptolemy (1898/1903), and Hero of Alexandria (1899). Many of his editions are still in use today.
The French Academy of Sciences awarded him the Prix Binoux for 1912.
His sister married biochemist Max Henius.
Heiberg inspected the vellum manuscript in Constantinople in 1906, and realized that it contained mathematical works by Archimedes that were unknown to scholars at the time.
Heiberg's examination of the manuscript was with the naked eye only, while modern analysis of the texts has employed x-ray and ultraviolet light. The Archimedes Palimpsest is currently stored at the Walters Art Museum in Baltimore, Maryland.