Jędrzej Śniadecki (archaic English: Andrew Sniadecki; 30 November 1768 – 12 May 1838) was a Polish writer, physician, chemist and biologist. His achievements include the creation of modern Polish terminology in the field of chemistry.

Śniadecki was born in Żnin in the Polish-Lithuanian Commonwealth. After completing his university studies, he was chosen to be the first professor of medicine and chemistry at the Grand Duchy of Lithuania's "Main School," which in 1803 was renamed the Imperial University of Vilna. One of his students was Ignacy Domeyko. Śniadecki was also one of the main organizers and head of the recently created Wilno Medical-Surgical Academy. From 1806-36 he headed the local Medical Scientific Society, one of the premier scientific societies in the region.

Śniadecki's most important book was Początki chemii (The Beginnings of Chemistry), the first Polish-language chemistry textbook, prepared for the Commission of National Education. It was considered one of the best Polish scientific textbooks of the age and was used in Polish universities well into the 1930s. Śniadecki was also known as a writer of less serious works; a co-founder of Towarzystwo Szubrawców (the Wastrel Society), he contributed articles to its satirical weekly, Wiadomości Brukowe (The Gutter News). He also wrote copiously in Wiadomości Wileńskie (The Vilnius' News), the largest and most prestigious daily in Vilnius.

In 1807, Śniadecki announced he had discovered a new metal in platinum and called it "vestium". Three years later, Académie de France published a note saying that the experiment could not be reproduced. Discouraged by this, Śniadecki dropped all his claims and did not talk about vestium anymore. Nevertheless, there have been speculations that this new element was ruthenium, found thirty-seven years later by Karl Klaus. However, they are not accepted by modern sources.

Jędrzej was the brother of Jan Śniadecki and father of Ludwika Śniadecka. He died in Vilnius and is buried at the Rasos Cemetery.