Baltic German diplomat who played a key role in the initiation of the Northern War (Northern War, Second) (1700–21).

Born to the Livonian (Livonia) German gentry, Patkul entered the Swedish army in Livonia in 1687. After serving as a representative of the Livonian landowners to the Swedish court in 1690–91, Patkul was arrested and sentenced to death for sedition by the Swedes in 1694 for airing the Livonians' grievances over land questions. He escaped to western Europe, however, via Courland.

Making the acquaintance of highly placed Saxon officials in 1698, Patkul gained an audience in the following year with King Augustus II of Poland (who was also the elector of Saxony), during which he interested the king in a Saxon-Russian alliance against Sweden. Patkul then led negotiations that resulted in the Saxon-Polish-Russian-Danish coalition, which started the Northern War against Sweden in 1700. Patkul entered the Russian diplomatic and military service in 1703, and thereafter he tried unsuccessfully to bring Prussia into the war. In 1707, after angering the Saxons by intriguing with Austria, he was delivered to the Swedish forces in Poland and tortured to death at Kazimierz for desertion and treason.