Thomas à Kempis, C.R.S.A. (Thomas van Kempen or Thomas Hemerken or Haemerken, litt. "Hammerkin" (small hammer); c. 1380 – 25 July 1471) was a Dutch canon regular of the late medieval period and the author of The Imitation of Christ, one of the most popular and best known Christian books on devotion. His name means Thomas "of Kempen", his hometown, and in German he is known as Thomas von Kempen. He also is known by various spellings of his family name: Thomas Haemerken; Thomas Hammerlein; Thomas Hemerken and Thomas Hämerken.