Johann Buckholdt [properly Beukelsz, or Bockelszoon], (c. 1508-1535), Dutch Anabaptist fanatic, better known as John of Leiden, from his place of birth, was the illegitimate son of Bockel, burgomaster of Soevenhagen, who afterwards married his mother. He was born about 1508, apprenticed to a tailor, became infected with the opinions of Thomas Münzer, travelled in pursuit of his trade (being four years in London), married a widow, became bankrupt, and in September 1533 joined the Anabaptist movement under Johann Matthysz (Matthyszoon), baker of Haarlem. He had little education, but some literary faculty, and had written plays. On the 13th of January 1534 he appeared in Münster as an apostle of Matthysz. Good-looking and fluent, he fascinated women, and won the confidence of Bernard Knipperdollinck, a revolutionary cloth merchant, who gave him his daughter in marriage. The Münster Anabaptists took up arms on the 9th of February 1534 (see Anabaptists). On the death of Matthysz (1534), Buckholdt succeeded him as prophet, added his widow to the number of his wives, and organized a new constitution for Münster, with twelve elders (suggested by the tribes of Israel) and other officers of a theocracy, but soon superseded these, making himself king of the new Zion. His arbitrary rule was marked by pomp and severity.
Münster was retaken (June 25, 1535) by its prince-bishop, Franz von Waldeck. Buckholdt, after many indignities, was cruelly executed on the 22nd of January 1536; his body, and those of his companions, were hung in cages to the tower of the Lamberti church. His portrait is in Grouwelen der Hooftketteren (Leiden, 1607; an English edition is appended to Alexander Ross's Pansebeia, 2nd ed., 1655); a better example of the same is given by Arend.
See Arend, Algemeene Geschiedenis des Vaderlands (1846), ii., iii., 629; Van der Aa, Biographisch Woordenboek der Nederlanden (1853); E. Belfort Bax, Rise and Fail of the Anabaptists (1903).