Hermann Balk (? - died March 5, 1239, Würzburg), also known as Hermann von Balk or Hermann Balke, was a Knight-Brother of the Teutonic Order and its first Landmeister, or Provincial Master, in both Prussia and Livonia. From 1219 to 1227, he served as the Deutschmeister in the Order's Province of Alemannia. Balk led the crusaders during the Prussian Crusade and became Master of Prussia in 1230. From 1237 to 1238, he also served in the additional role as Master of Livonia.
Balk came from a family of Lower Saxon-Markish origin. He may have been a former canon at Hildesheim and may have joined the Teutonic Knights at Acre in 1189. He was well respected by fellow Roman Catholics, but he had no patience for pagans. His leadership and traditions were emulated by his successors throughout the 13th century, and he created the master's seal presenting the flight into Egypt. While all other masters' seals were anonymous, only Balk's included his name.
In 1226, the Teutonic Knights were invited to combat the Old Prussians by Duke Conrad I of Masovia, whose lands had been raided by the pagans over the preceding decades. Balk led the first substantial detachment of Teutonic Knights to Castle Vogelsang near Toruń. The master allegedly negotiated the Treaty of Kruszwica with Conrad in 1230, by which the Teutonic Knights would control Culmerland and future conquests instead of them passing to the Masovian duke or Bishop Christian of Oliva; the arrangement was similar to what had been agreed upon by Emperor Frederick II in the 1226 Golden Bull of Rimini.