Animalia Paradoxa (Latin for "contradictory animals"; cf. paradox) are the mythical, magical or otherwise suspect animals mentioned in early editions of Carl Linnaeus' seminal work Systema Naturae under the header "Paradoxa" (see cryptid). It lists fantastic creatures found in medieval bestiaries as well as those reported by explorers from abroad and gives explanations to why they are excluded from Systema Naturae. According to Swedish historian Gunnar Broberg, it was to offer a natural explanation and demystify the world of superstition. Paradoxa was dropped from Linnaeus' classification system as of the 6th edition (1748).
Included in the 1st (1735) edition:
- Hydra: in 1735 Linnaeus inspected the alleged remains of a Hydra in Hamburg which turned out to be made from weasels and snake skins.
- Rana-Piscis: a South American frog which is significantly smaller than its tadpole stage; it was thus (incorrectly) reported to Linnaeus that the metamorphosis in this species went from 'frog to fish'. In the 10th edition of Systema Naturae, Linnaeus named the species Rana paradoxa, though its genus name was changed in 1830 to Pseudis.
- Monoceros is in reality Monodon.
- Pelecanus: "Linnaeus thought [pelicans] might reflect the over-fervent imaginations of New World explorers"
- Satyrus: Linnaeus wrote "with a tail, hairy, bearded, with a manlike body, gesticulating much, very fallacious, is a species of monkey, if ever one has been seen."
- Borometz (aka Scythian Lamb) "Linnaeus [...] had seen a faked vegetable lamb taken from China to Sweden by a traveler"
- Bernicla (aka Scottish Goose) Frederick Edward Hulme noted: "[The] barnacle-goose tree was a great article of faith with our ancestors in the Middle Ages."
- Draco: Linnaeus wrote that it has a "snakelike body, two feet, two wings, like a bat, which is a Lacerta alata or a ray artificially shaped as a monster and dried."
- Automa Mortis Linnaeus wrote "The DEATH-WATCH produces the sound of a smaller clock in walls, is named Pediculus pulsatorius, which perforates wood and lives in it".
Four taxa were added in the 2nd (1740) edition:
- von Linné, C. (1744). Caroli Linnæi medic. & botan. in acad. Upsaliensi professoris ... Systema naturæ: In quo proponuntur naturæ regna tria secundum classes, ordines, genera & species. Sumptibus Michaelis-Antonii David. p. 102. Retrieved 2015-04-05.
- Tore Frängsmyr, Sten Lindroth, Gunnar Eriksson & Gunnar Broberg (1983). Linnaeus, the man and his work. Berkeley and Los Angeles: University of California Press. pp. 176–177. ISBN 0-7112-1841-2.
- Sandra Knapp (2002). "Fact and fantasy". Nature 415 (6871): 479. Bibcode:2002Natur.415..479K. doi:10.1038/415479a. Also available on Scribd.
- S. W. Garman (1877). "Pseudis, the paradoxical frog". The American Naturalist 11 (10): 587–591. doi:10.1086/271961. JSTOR 2447862.
- Andy Dobson, Kevin D. Lafferty, Armand M. Kuris, Ryan F. Hechinger & Walter Jetz; Lafferty; Kuris; Hechinger; Jetz (2008). "Homage to Linnaeus: How many parasites? How many hosts?" (PDF). Proceedings of the National Academy of Sciences 105 (Suppl. 1): 11482–11489. Bibcode:2008PNAS..10511482D. doi:10.1073/pnas.0803232105. PMC 2556407. PMID 18695218.
- Carl Linnaeus, Systema naturae (1735; facsimile of the first edition), trans. M. S. J. Engel-Ledeboer and H. Engel (Nieuwkoop, Netherlands: B. de Graaf, 1964), 30. via 
- Jan Bondeson (1999). "Spontaneous generation". The Feejee Mermaid and Other Essays in Natural and Unnatural History. Cornell University Press. pp. 193–249. ISBN 978-0-8014-3609-3.
- Hulme, F.E. (1886). Myth-land. S. Low, Marston, Searle & Rivington. p. 168. Retrieved 2015-04-05.
- von Linné, C. (1740). Systema naturae in quo naturae regna tria: secundum classes, ordines, genera, species, systematice proponuntur. Apud G. Kiesewetter. p. 66. Retrieved 2015-04-05.