Jonas Michaelius (born in 1577; died in Holland after 1638) was the first clergyman to lead a congregation of the Dutch Reformed Church in America.
He was educated at the University of Leyden, and settled as a clergyman in Holland in 1612-1616, in San Salvador in 1624-1625, and in Guinea in 1626-1627. He went to New Amsterdam in 1628, and was thus the first minister of the Dutch Reformed Church in the United States. He organized a consistory, and administered the sacraments, but returned to Holland in a few years, probably before the arrival of his successor, Everardus Bogardus, in 1633.
Michaelius' wife died in New Amsterdam shortly after his arrival. The classis of Amsterdam wished to send Michælius back to the United States in 1637, but he did not return.
It was long supposed that Bogardus was the first Reformed Church clergyman in the United States, but the precedence of Michælius was established by a letter from him to Adrian Smoutius, dated New Amsterdam, 11 August 1628, which was found in the late 19th century in the Dutch archives at the Hague. In this letter he describes the degraded state of the natives, and proposes to educate their children without trying to redeem the parents. The letter is printed in an appendix to Mary L. Booth's History of the City of New York (New York, 1859).