Prince Krzysztof Radziwiłł, epithet "Piorun" ("Lightning") (Lithuanian: Kristupas Radvila „Perkūnas“, 1547–1603) was a Reichsfürst of the Holy Roman Empire and a member of the nobility of the Polish–Lithuanian Commonwealth.

[1] Radziwiłł was one of the most talented commanders in the service of the Polish–Lithuanian Commonwealth during the wars against Muscovy and Sweden, and won the Battle of Kokenhausen.

[1] He received the epithet "Piorun" (translated as "Lightning" or "Thunderbolt") for his deadly and very successful cavalry raids against Ivan the Terrible's forces in Russian Tsardom territory during the Livonian War, forcing it to capitulate.

[citation needed] His achievements, combined with his powerful Radziwiłł family backing, helped him rise to his various voivode and starost offices and further increased his family's wealth.

[1] Like his father, brother, and nephew, he was an ardent Calvinist and adherent of the Polish Reformed Church, and defended it against the rise of the Counter-Reformation.