At the center of Reformation studies sits the towering Martin Luther. Luther not only kick-started the Reformation, he is also one of the more influential people in modern history. The standard biography is Roland Bainton’s classic Here I Stand: A Life of Martin Luther. Yale historian Bainton positions Luther within his historical context, recounts his personal theological struggles, and develops the specifics of his emerging theological system. Very colorful in tone and substance, this is a classic starting point for Martin Luther studies. Less a full biography than an analysis of how historic medieval theology influenced Luther is Heiko Oberman’s Luther: Man between God and the Devil. Oberman analyzes Luther the person as much as Luther the theologian and scholar, and sets Luther, who passionately believed that he was in a moral struggle with the Devil, firmly within his medieval world. This work especially helps to show how Luther was a product of his time as well as a Reformer who pushed against conformity.
In Luther’s Theology of the Cross: Martin Luther’s Theological Breakthrough, a succinct study of Luther between the years 1509 and 1519, Alister McGrath focuses particularly on his theological concept of the “theology of the cross,” which shaped his doctrine of justification. For Luther, this struggle became the key to unlocking his theological system. Developing this further is Gerhard O. Forde’s On Being a Theologian of the Cross, which studies Luther’s Heidelberg Disputation of 1518. Gerhard explores this crucial Lutheran doctrine by distinguishing between a “theology of glory,” which tends to minimize the ugly side of the human condition, and a “theology of the cross,” which embraces a realistic view of sin and evil.
The fifteen solid essays in editors R.C. Sproul and Stephen Nichols’s The Legacy of Luther reexamines Luther’s home life, his theology, his standing among other Reformers, his role as pastor, and the state of modern Lutheranism. Leppin Volker’s short, concise Martin Luther: A Late Medieval Life is not a standard biography; rather, it focuses on Luther’s continuities with medieval Catholic thought and how his theology transitioned over time. This should be read alongside Martin Luther and the Enduring Word of God: The Wittenberg School and Its Scripture-Centered Proclamation, by Robert Kolb, which examines the new intellectual and theological climate that Luther created. Finally, the best modern biography is Scott Hendrix’s Martin Luther: Visionary Reformer. This comprehensive work relies heavily on Luther’s correspondence and the latest research, and is especially thorough in developing Luther’s theology.
Lastly, in addition to biographies, there are three notable works of collected essays. A solid collection on Luther’s theology can be found in editors Robert Kolb, Irene Dingel, and L’ubomir Batka’s The Oxford Handbook of Martin Luther’s Theology. For general essays regarding Luther and his theological offspring, see editor Timothy J. Wengert’s Dictionary of Luther and the Lutheran Traditions. Finally, Mark A. Lamport’s two-volume Encyclopedia of Martin Luther and the Reformation provides a panoramic series of essays that place Luther in a global context.
Luther's theology of the cross : Martin Luther's theological breakthrough by 
On being a theologian of the Cross : reflections on Luther's Heidelberg disputation, 1518 by 
Martin Luther and the enduring Word of God : the Wittenberg School and its Scripture- centered proclamation by 
