The House of Frohburg (also Froburg) was a noble family in medieval Switzerland, with possessions in what is now the canton of Solothurn. They originate in the Wigger basin, near Zofingen. In the 10th century, they built their "Frohburg" castle on a hill near Trimbach. They had the title of counts from the later 11th century. They ruled the lands between Olten and Solothurn, and took parts of Aargau and Sisgau as fief from the bishop of Basel. They reached the peak of their power in the later 12th and early 13th century, building a number of castles, and founding towns such as Aarburg, Liestal, Olten (then a fortified river crossing), Waldenburg, Wiedlisbach and Zofingen. They also founded Schöntal Abbey near Waldenburg. The House of Frohburg was divided into three branches, Neu-Homberg, Waldenburg and Zofingen, in c. 1250. The Zofingen branch was extinct in 1307, followed by the Neo-Homberg one in 1325. The Waldenburg branch survived for another 40 years but declined in influence, being forced to sell most of its possessions, most of them to the ascending House of Habsburg. The last count of Frohburg was Hermann VI (d. 1367 as abbot of St. Urban's Abbey).
Counts of Frohburg:
Wolfrad count of Frohburg (d. 1095)
Volmar count of Frohburg (mentioned 1114), son of Wolfrad, and thus presumably not identical with Volmar I below.
Volmar I. (b. c. 1050, d. 1114), son of Adalbero, count of Breisgau
Volmar II, son of Volmar I (mentioned 1143, d. after 1175)
Hermann I, son of Volmar I (fl. 1095–1125)
Hermann II, son of Volmar II (mentioned 1160, d. 1211/1213)
Ludwig III, son of Hermann II (mentioned 1196; d. 1256/1259); founder of the Frohburg-Zofingen branch
Hermann III, son of Hermann II (d. 1236/1237), founder of the Frohburg-Waldenburg branch
Hermann IV, son of Ludwig III (mentioned 1223, d. before 1253), founder of the Frohburg-Homberg branch
Friedrich, son of Hermann IV (d. before 1285), took the title of count of Homberg, see House of Homberg for his line.
Ludwig IV, son of Ludwig III (mentioned 1239–1257)
Ludwig V, son of Hermann III (mentioned 1240, died 1279)
Hermann V, son of Ludwig V (mentioned 1275–1291)
Volmar IV, son of Ludwig V (mentioned 1280, died 1320)
Johann, son of Volmar IV (mentioned 1318, d. 1366)
Hermann VI, son of Volmar IV (mentioned 1320, died 1367); abbot of St. Urban Abbey, inherited the title of count from his elder brother in 1367 but died in the following year. The last count of Frohburg.
