Jacob Christian Schäffer, alternatively Jakob, (31 May 1718 – 5 January 1790) was a German dean, professor of theology, botanist, mycologist, entomologist, ornithologist and inventor.

His work in natural sciences includes writing comprehensive and illustrated volumes on plants, fungi, birds, and insects, proposing new classification systems, and maintaining a museum of curiosities.

Schäffer also experimented with electricity, colours, and optics, manufactured prisms and lenses, and invented an early washing machine and other practical devices.

From 1762 to 1764, he wrote four richly illustrated volumes on mycology, Natürlich ausgemahlten Abbildungen baierischer und pfälzischer Schwämme, welche um Regensburg wachsen.

In 1779, Schäffer published the three-volume work Icones insectorum circa ratisbonam indigenorum coloribus naturam referentibus expressae,[6] which included 280 hand-coloured plates of copper engravings, illustrating approximately 3,000 insects.

[3] Jacob Christian Schäffers erleichterte Arzneykräuterwissenschaft: nebst vier Kupfertafeln mit ausgemahlten Abbildungen.

1770 Digital edition by the University and State Library Düsseldorf Schäffer organised a rich personal cabinet of curiosities, the Schaefferianum Museum, opened to the public and which Goethe (1749–1832) visited in 1786 at the time of the "voyage" which led him to Italy.

Schäffer maintained a correspondence with many naturalists including Carl von Linné (1707–1778) and René Antoine Ferchault de Réaumur (1683–1757).

The paper industry also interested him and between 1765 and 1771 the results of his observations and experiments were published as Versuche und Muster, ohne alle Lumpen oder doch mit einem geringen Zusatze derselben, Papier zu machen.