Was a leader in reforming the Catholic church.?

The answer is St. Ignatius of Loyola.

Catholic Answer

There were many leaders during the Counter-reformation:

The Counter-Reformation is the name given to the Catholic movement of reform and activity which lasted for about one hundred years from the beginning of the Council of Trent (q.v., 1545). Popes St. Pius V and Gregory XIII, Philip Neri, Charles Borromeo, St. Ignatius

from A Catholic Dictionary, edited by Donald Attwater, Second edition, revised 1957The Counter-Reformation is the name given to the Catholic movement of reform and activity which lasted for about one hundred years from the beginning of the Council of Trent (q.v., 1545), and was the belated answer to the threatening confusion and increasing attacks of the previous years. It was the work principally of the Popes St. Pius V and Gregory XIII and the Council itself in the sphere of authority, of SS. Philip Neri and Charles Borromeo in the reform of the clergy and of life, of St. Ignatius and the Jesuits in apostolic activity of St. Francis Xavier in foreign missions, and of St. Teresa in the purely contemplative life which lies behind them all. But these were not the only names nor was it a movement of a few only; the whole Church emerged from the 15th century purified and revivified. On the other hand, it was a reformation rather than a restoration; the unity of western Christendom was destroyed; the Church militant (those still on earth) led by the Company of Jesus adopted offence as the best means of defence and, though she gained as much as she lost in some sense, the Church did not recover the exercise of her former spiritual supremacy in actuality.