Ernst Johann Otto Hartert (29 October 1859 – 11 November 1933) was a widely published German ornithologist.

The article On a collection of Humming Birds from Ecuador and Mexico appears to be their only joint publication.

[1] Hartert published the quarterly museum periodical Novitates Zoologicae (1894–39) with Rothschild, and the Hand-List of British Birds (1912) with Francis Charles Robert Jourdain, Norman Frederick Ticehurst and Harry Forbes Witherby.

He wrote Die Vögel der paläarktischen Fauna (1910–22) and travelled in India, Africa, and South America on behalf of his employer.

[4] Among the written publications of Ernst Hartert are:[5] A species of lizard, Hemiphyllodactylus harterti, and 12 birds are named in his honor.