Princely count William III of Henneberg-Schleusingen (12 March 1434 – 25 May 1480 in Salorno) was a member of the House of Henneberg.

William III inherited the princely county of Henneberg in 1440, when his father died in a hunting accident.

[3] Apparently out of personal piety, William promoted pilgrimages and founded churches and monasteries.

In 1482, his body was transferred to the Henneberg family vault in the church of the monastery at Kloster Veßra.

[5] The epitaph in Bolzano was sculpted by Erasmus Forster in Gardolo near Trento and installed in the Church in 1495 or 1496.