Beginning with 95 Theses of  Martin Luther

Protestant Old Testament contains 39 books(Hebrew Masoretic Text) whereas the Roman Catholic Old Testament(based on Septuagint) contains 46 books

Protestant  Leaders

John Calvin
Jan Huss
Martin Luther
John Wyclife

Zwingli, Tyndale, Melanchthon, Beza, Bucer, Bullinger, Chemnitz, Episcopius, Oecolampadius, Cranmer, Menno Simons, Arminius.

Protestant Groups

Lutheran, Reformed, Anglican, Presbyterian, Baptist, Anabaptist, Puritan, and Congregationalist traditions.