Wolter von Plettenberg (or Walter von Plettenberg) was the Master of Livonian Order 1494–1535 was one of the greatest leaders of Livonian knights. His family had origins in Westphalia. He went to the fort of Narva at the age of ten. As the marshal of order, he fought successfully against the city of Riga and was elected master in 1494. The same year Muscovites closed down Hanseatic office in Novgorod and imprisoned German merchants there. Livonia was difting into war with Muscovite Russia.

In the war with Russia 1499-1503 Plettenberg showed himself as a talented and skilled commander. His strenght lay in his skilful use of heavy cavalry and artillery fire. With such tactics Plettenberg won, for instance, the battle of the Seritsa River, where an Order army of 8,000 foot and 4,000 horse defeated 40,000 Muscovites.

He captured several Russian cities, like Pskov, Ostrov, Izborsk, Ivangorod and besieged Novgorod but failed to protect Livonia against devastating Russian raids. Plettenberg made alliance (treaty of Wenden) with Lithuanian prince Alexander against Russians. He even tried to convince the Pope Alexander VI to issue crusading bull against Russians. Finally he made peace with Muscovian grand prince Ivan III in Pskov 1503 with no territorial changes.

During Reformation, Plettenberg supported the Lutheranism hoping thus to make himself independent of the Archbishop of Riga. The province was in disarray and master had serious difficulties in ruling the territory which remained divided between the Order, bishoprics and rich cities. In 1525 Plettenberg converted himself and the Order to the Lutheran faith, but he refused to secularize the province as Teutonic Order in Prussia had done.

He died in 1535.