Thomas à Kempis (orig. Thomas Haemerkken; Thomas Hammerlein; also Thomas Hemerken, Thomas Hämerken, Thomas van Kempen, Tomás de Kempis) (ca.1380 - July 25, 1471) was a late Medieval Catholic monk and author of Imitation of Christ, one of the best known Christian books on devotion.

He was born at Kempen (Germany), County of Cleves in 1380 and died in 1471 near Zwolle in the Prince-Bishopric of Utrecht, 75 miles north of his birthplace. He was apparently (accidentally) buried alive, in that splinters were later found embedded under the fingernails of his corpse. He was denied canonization on the grounds that a saint would not fight death in this way.[1] His paternal name was Hemerken, Kleverlandish for "little hammer."

In 1395 he was sent to the school at Deventer conducted by the Brethren of the Common Life. He became skillful as a copyist and was thus enabled to support himself. Later he was admitted to the Augustinian convent of Mount Saint Agnes near Zwolle, where his brother John had been before him and had risen to the dignity of prior. Thomas received priest's orders in 1413 and was made subprior in 1429.

The house was disturbed for a time in consequence of the pope's rejection of the bishop-elect of Utrecht, Rudolf van Diepholt; otherwise, Thomas' life was a quiet one, his time being spent between devotional exercises, composition, and copying. He copied the Bible no less than four times, one of the copies being preserved at Darmstadt in five volumes. In its teachings he was widely read, and his works abound in Biblical quotations, especially from the New Testament.

His life is no doubt fitly characterized by the words under an old picture first referred to by Francescus Tolensis: "In all things I sought quiet and found it not save in retirement and in books." A monument was dedicated to his memory in the presence of the archbishop of Utrecht in St. Michael's Church, Zwolle, on November 11, 1897. Because of the closing of the church, his shrine was replaced in 2006 in an historical church in the centre of Zwolle.

Thomas à Kempis belonged to the school of mystics who were scattered along the Rhine from Switzerland to Strasburg and Cologne and in the Netherlands. He was a follower of Geert Groote and Florentius Radewijns, the founders of the Brethren of the Common Life.

His writings are all of a devotional character and include tracts and meditations, letters, sermons, a life of Saint Lydewigis, a Christian woman who remained steadfast under a great stress of afflictions, and biographies of Groote, Radewijns, and nine of their companions. Works similar in content to the Imitation of Christ and pervaded by the same spirit are his prolonged meditation on the life and blessings of the Savior and another on the Incarnation. Both of these works overflow with adoration for Christ.