Nicholas Kratzer (1487? – 1550) was a German mathematician, astronomer, and horologist. Much of Kratzer's professional life was spent in England, where he was appointed as astronomer to King Henry VIII.
Born in Munich in 1487, Kratzer came to England in 1516 and established himself as part of the artistic and scientific circle around Sir Thomas More. Kratzer tutored More's children in mathematics and astronomy and More introduced him at court in much the same way as he had their mutual friend Hans Holbein. In the same manner as Holbein, Kratzer's talents obtained him a court position as astronomer and clock maker to the king.
Kratzer also collaborated with Holbein on producing maps, and in return the artist produced a portrait of Kratzer in 1528 that now hangs in the Louvre; it depicts the craftsman surrounded by the tools of his trade. His close relationship with Holbein and More also may be observed in his annotations of Holbein's draft for his portrait of the More family. Kratzer identifies the various family members and their ages for the benefit of More's friend, the theologian Erasmus.