Wigger I (died 981) was the father of a line of counts ruling from his new castle of Bilstein, west of Albungen (today part of Eschwege) to the Werra.
The counts of Bilstein played a prominent role in Thuringia from 967 to 1301 and were third after the Ekkehardinger and Weimar-Orlamünde in terms of power and influence.
He had extensive estates — Langensalza, Mühlhausen, Schlotheim, Frieda, Dornburg an der Saale, and Eschwege — and comital authority in the Eichsfeld and the middle Werra.
He was count of the Germarmark (east of Mühlhausen), Weitagau, and Ducharingau (area of Zeitz and Naumburg).
He participated in their wars on the Slavic peoples to the east and was created count in the Plisnagau and the Puonzowagau.