Johannes Andreas August Grabau (March 18, 1804—June 2, 1879) was an influential German-American Old Lutheran pastor and theologian.

[1] After three years as a teacher in Magdeburg and Sachsa bei Nordhausen, Grabau was ordained and installed as pastor of St. Andrew's Church in Erfurt in June 1834.

Grabau was jailed twice for refusing to use the Prussian union Agenda and was permitted to immigrate to America in summer 1839 with members of Lutheran congregations in Erfurt and Magdeburg.

[2] Grabau was married on July 15, 1834, to Christine Sophia Burgraf, the daughter of Johann Andreas Burggraf and Friedericke Louise Elizabeth Beulke.

Grabau died on June 2, 1879, in Buffalo, New York, shortly before the 40th anniversary of his arrival in the United States.