John Caradja or John George Caradja (Greek: Ἰωάννης Γεώργιος Καρατζάς, Ioannis Georgios Karatzas; Romanian: Ioan Gheorghe Caragea; French: Jean Georges Caradja; 1754, Constantinople – 1844, Athens) was a Phanariote Prince of Wallachia, who reigned between 1812 and 1818. He became famous due to the code of law known as the Legiuirea Caragea ("Caragea's Law" or "Caradja's Law"), which was the first modern code of the Danubian Principalities, but also because of the effective measures taken during the bubonic plague outbreak of 1813. The epidemic became commonly known as Caragea's plague.
A member of the Caradja family, he was related to the Mavrocordatos. His nephew, Prince Alexander Mavrocordatos, was Court Secretary in Bucharest under his rule. Together with his uncle, Alexander Mavrocordatos went into exile to the Italian Peninsula, via the Austrian Empire (1818).
Caradja was named Prince by the Ottoman authorities in 1812, under the rule of Sultan Mahmud II. According to the report of the Imperial French Ambassador to Constantinople, in order to become hospodar, Caradja had to pay 8,000 bags of gold (4 million lei). During the first night he spent in Bucharest, the princely residence of Dealul Spirii (Curtea Nouă) burnt down.