ORP Piorun was an N-class destroyer operated by the Polish Navy in World War II. The word piorun is Polish for "Thunderbolt". Ordered by the Royal Navy in 1939, the ship was laid down as HMS Nerissa before being loaned to the Poles in October 1940 while still under construction.

The J, K and N class consisted of 24 destroyers built for the Royal Navy beginning in 1938. They were a return to a smaller vessel, with a heavier torpedo armament, after the Tribal class that emphasised guns over torpedoes. The ships were built in three flotillas or groups, each consisting of eight ships with names beginning with "J", "K" and "N". The flag superior of the pennant numbers changed from "F" to "G" in 1940.