Caspar (or Kaspar) Schwen(c)kfeld von Ossig (1489 or 1490 – December 10, 1561) is a German theologian, writer, and preacher who becomes a Protestant Reformer and spiritualist, one of the earliest promoters of the Protestant Reformation in Silesia.

Schwenckfeld comes to Reformation principles through Thomas Müntzer and Andreas Karlstadt.

However, he develops his own principles and falls out with Martin Luther over the eucharistic controversy (1524).

He has his own views on the sacraments—the Heavenly Flesh doctrine—developed in close association with his humanist colleague, Valentin Crautwald (1465–1545).

His followers become a new sect, which is outlawed in Germany, but his ideas influence Anabaptism, Pietism on mainland Europe, and Puritanism in England.