Michael Friedrich Graf von Althann (12 July 1680, Glatz, Prussia (now Kłodzko, Poland) – 20 June 1734, Waitzen, Habsburg monarchy (now Vác, Hungary)) was a Holy Roman clergyman and politician who was the bishop of Vác (or Waitzen) and former viceroy to the Kingdom of Naples and Sicily.
He attended the Jesuit College in Glatz and studied theology in Olomouc, Wrocław, and the Collegium Germanicum et Hungaricum in Rome.
In 1718, he was appointed bishop of Vác in Hungary, and a year later he received the cardinal dignity with the Roman titular church Santa Sabina at Aventine Hill.
appointed him to be the viceroy of Naples and Sicily, who had come to the Austrian Habsburgs in the Treaty of Utrecht as a result of the Spanish War of Succession.
Immediately after his appointment as Bishop of Vác, von Althann initiated the reconstruction of his diocese, which had been greatly affected by the Ottoman wars in Europe and whose administration had largely collapsed.
In modest means, he built the episcopal residence and the priest's seminary in Vác and donated a hospital.