Johan, Johann, or Johannes Hartmann may refer to:
Johannes Hartmann (1568–1631), German chemist Johannes Franz Hartmann (1865–1936), German physicist and astronomer Johann Hartmann (1726–1793), Danish composer Johan Ernst Hartmann (1770–1844), Danish composer Johan Peter Emilius Hartmann (1805–1900), Danish composer
See also
Carl Johan Hartman (1790–1849), Swedish physician and botanist
Hartmann Hartman John Hartmann John Hartman (disambiguation)