German poet who helped make mid-17th-century Nürnberg a centre of German literature.

Klaj studied theology at the University of Wittenberg and then went to Nürnberg, where, with Georg Philipp Harsdörfer (Harsdörfer, Georg Philipp), he founded in 1644 the literary society known as the Pegnesischer Blumenorden (“Pegnitz Order of Flowers”). He taught at Nürnberg, and in 1650 he went as teacher and preacher to Kitzingen. He specialized in pastoral poetry, often using ingenious internal rhyme schemes, and wrote, with Harsdörfer, the Pegnesisches Schäfergedicht (1644; Pegnitz Idyll) and the Fortsetzung der Pegnitzschäferey (1645; The Pursuit of Pegnitz's Meadows). He also specialized in religious oratorios and mystery plays, such as Die Auferstehung Jesu Christi (1644; The Resurrection of Jesus Christ), Freudengedicht auf die Geburt Christi (1645; Joyful Verses on the Birth of Christ), Trauerspiel vom leidenden Christus (1645; The Tragedy of the Sorrows of Christ), and Herodes der Kindermörder (1645).