Johann Nepomuk Czermak (17 June 1828 – 16 September 1873) was an Austrian-German physiologist who was a native of Prague.
He studied in Prague, Vienna, Breslau and Würzburg.
At Breslau he was greatly influenced by the work of physiologist Jan Evangelista Purkyne (1787–1869).
He became a professor at Graz in 1855, and proceeded to work at several European universities, including Krakow (1856/57) and Leipzig (from 1869).
Just prior to his death in 1873, he founded a physiological institute in Leipzig called the "Spectatorium".
Czermak was a member of the Austrian Academy of Sciences.