Jakub Wejher (or Weyher, German Jakob Weiher) (1609 – 1657), was a member of the Polish line of the Weyher family, a Count of the Holy Roman Empire and member of the Polish–Lithuanian Commonwealth szlachta (nobility). His coat of arms was Wejher (also known as Skarzyna). Wejher was the Castellan of Puck and Voivode of Malbork (Marienburg) from 1643–1657, the Castellan of Chmielno, and the Starost of Człuchów, Kiszporek, Bychów and Brzechowo. He is remembered as a pious and tolerant magnate and an experienced military leader.
Weiher was one of eight sons of Jan Wejher (1580–1626) and Anna Szczawińska, and brother of Mikołaj Wejher (?–1647) and Ludwik Wejher (?–1656).
He was a member of a rich magnate family originating from Westphalia, some of whom had moved to Farther Pomerania where they have been recorded since 1234. Martin Weyher was a Lutheran Bishop of Cammin. From the first half of the 16th century members of the family started to hold many offices in the Kingdom of Poland and later on in the Polish–Lithuanian Commonwealth. They intermarried into Polish nobility and became its prominent members. Jakub became a courtier of prince Władysław IV Vasa. He studied first at a Jesuit College in Braniewo, Royal Prussia, a province of the Polish–Lithuanian Commonwealth, then abroad at the University of Bologna. He was a Catholic and a supporter of the Counter-Reformation. Pursuing traditions of his family, as a youth he joined foreign military. In the years 1628-1632 he fought in the Thirty Years' War in the Holy Roman Empire in the armies of the Catholic League, commanding a cavalry unit under Albrecht von Wallenstein. At some point he visited Malta. For his valor he received the title count of the Holy Roman Empire (in 1636).