Tapper was born at Enkhuizen, County of Holland, on 15 February 1487. He matriculated at Leuven University on 11 June 1503, and graduated M.A. in 1507. While studying Theology he taught physics and logic. He was ordained to the priesthood in 1515, and graduated Licentiate of Sacred Theology on 3 June 1516 and Doctor of Sacred Theology on 16 August 1519.
Tapper was also the senior representative of the Inquisition of the Netherlands in Leuven where he acquired a particularly bad name as a cruel inquisitor, noted for a blind fanaticism and clever eloquence particularly suited to this spiteful office. An early history of the Reformation quotes him as follows:
It is no great matter whether those that die on this account be guilty or innocent, provided we terrify the people by these examples; which generally succeeds best, when persons eminent for learning, riches, nobility or high stations, are thus sacrificed.
Tapper was well respected by the Habsburg Emperor Charles V, who sent him to represent the Low Countries at the Council of Trent in 1551. After 1555, the successor of Charles, Phillip II, was not at all well disposed to him and he went into decline, dying in Brussels on 2 March 1559. He was buried in St Peter's church, Leuven.
- Methodus confessionis (Antwerp, Joannes Laet, 1553) Available on Google Books
- Declaratio articulorum a veneranda facultate theologiae Louaniensis: adversus nostri temporis Haereses, simul & earundem reprobatio (Lyon, Maurice Roy and Louis Pesnot, 1554) Available on Google Books
- Explicationes in articulos circa ecclesiastica dogmata, hoc seculo controversa (2 vols., Leuven, 1555)
- Opera omnia (2 vols., Cologne, Birckmann office, 1582) Available on Google Books
- Peter G. Bietenholz and Thomas Brian Deutscher (eds.), Contemporaries of Erasmus: A Biographical Register, vols. 1-3 (University of Toronto Press, 2003), 308-309.
- Jacob Cornelis van Slee, "Tapper, Ruard", in Allgemeine Deutsche Biographie, vol. 37 (1894), 396. Accessed 3 January 2018.
- Brandt, Geeraert; Chamberlayne, John (1740), The History of the Reformation and Other Ecclesiastical Transactions in and about the Low-Countries, T. Wood