|Died||21 May 1883 (aged 71)|
Johann August Ludwig Preiss (b. 21 November 1811, d. 21 May 1883) was a German-born British botanist and zoologist.
Preiss was born in Herzberg am Harz. He obtained a doctorate, probably at Hamburg, then emigrated to Western Australia. He arrived at the Swan River Colony on board the Britmart on 4 December 1838, remaining there until January 1842; during this time he became a British subject.
During his time in Western Australia, Preiss collected about 200,000 plant specimens, containing from 3,000 to 4,000 species.  His collections, together with those of James Drummond, formed the basis for early study of Western Australian flora. In 1842, he left Western Australia for London, where he broke up and sold his plant collection to recoup his costs. Various botanists published species based on his specimens, and these were later collated by Johann Lehmann to form the multi-volume Plantae Preissianae Sive Enumeratio Plantarum Quas in Australasia Occidentali et Meridionale Occidentali Annis 1838-41 Collegit L, published in Hamburg between 1844 and 1848.
The specimens collected by Preiss were not limited to plants: they included birds, reptiles, insects and molluscs. The molluscs were described by Karl Theodor Menke and published in Hanover in 1843 titled Molluscorum Novae Hollandiae Specimen. In October 1839, Preiss tried to sell his collection of bird skins to the colonial government in Perth, but it was declined. Preiss's collection of animals was sold in parts throughout Europe to museums and collectors. The only distinguishable collection of any note, still extant, is in the Municipal Museum of Halberstadt.  The collection of bird skins, representatives of 181 species, was also distributed to various museums; one set that was viewed in 1937 at Hamburg's Zoölogical Museum was lost when the building was destroyed in the subsequent bombing campaigns at the city. 
The first specimen of the Western Swamp Tortoise was collected by Preiss in 1839 and sent to the Vienna Museum where it was labelled New Holland, but was not named Pseudemydura umbrina until 1901 by Seibenrock. No further collections of the species were recorded until 1953. 
Preiss returned to Herzberg am Harz in 1844 and settled there. He died there on 21 May 1883. It had been on his recommendation that Ferdinand von Mueller moved to Australia in 1847.
Preiss is commemorated in the names of about 100 species of flora in Western Australia, including plants in the genera Acacia, Allocasuarina, Eucalyptus, Grevillea, Hakea, Kunzea, Melaleuca, Santalum, Xanthorrhoea and Callitris.
- J. H. Calaby. (1967) Preiss, Johann August Ludwig (1811–1883) Australian Dictionary of Biography accessed 2 February 2007
- Hall, Norman (1978). Botanists of the Eucalypts. Australia: Commonwealth Scientific and Industrial Research Organisation. ISBN 0643002715.
- Stearn, WT (1939) Lehmann's "Plantae Preissianae". Journal of the Society for the Bibliography of Natural History 1, 203-205.
- Preiss, JA Ludwig - botanical collector Australian Nation Botanical Gardens(Biography)
- Calaby, ADB
- Serventy, D. L.; Whittell, H. M. (1951). A handbook of the birds of Western Australia (with the exception of the Kimberley division) (2nd ed.). Perth: Paterson Brokensha.
- National Recovery Plan for the Western Swamp Tortoise (Pseudemydura umbrina) Dept Environment and Water Resources
- IPNI. L.Preiss.