John Marbeck, Merbeck or Merbecke (c. 1510 – c. 1585) was an English theological writer and musician who produced a standard setting of the Anglican liturgy. He is also known today for his setting of the Mass, Missa Per arma justitiae.
Probably a native of Beverley in Yorkshire, Merbecke appears to have been a boy chorister at St. George's Chapel, Windsor, and was employed as an organist there from about 1541. Two years later he was convicted with four others of heresy and sentenced to be burnt at the stake, but received a pardon owing to the intervention of Stephen Gardiner, Bishop of Winchester. An English Concordance of the Bible which Merbecke had been preparing at the suggestion of Richard Turner, was however confiscated and destroyed. A later version of this work, the first of its kind in English, was published in 1550 with a dedication to Edward VI.
In the same year, Merbecke published his Booke of Common Praier Noted, intended to provide for musical uniformity in the use of the First Prayer Book of Edward VI. This set the liturgy to semi-rhythmical melodies partly adapted from Gregorian chant; it was rendered obsolete when the Prayer Book was revised in 1552. Merbecke wrote several devotional and controversial works of a strongly Calvinistic character, and a number of his musical compositions are preserved in manuscript in the British Library, and at Oxford and Cambridge. He died, probably while still organist at Windsor, about 1585.