Robert Charles Sproul (/sproʊl/ SPROHL; February 13, 1939 – December 14, 2017) was an American Reformed theologian, Christian apologist, and Presbyterian pastor. Being the founder and first chairman of Ligonier Ministries, Sproul could be heard daily on the Renewing Your Mind radio broadcast internationally.

Working as a staunch defender of Protestantism, Sproul saw emerging modern technologies as an opportunity to disseminate teaching on Reformed theology. Faced with an increase in ecumenical activity between evangelical and Catholic figures in the 1990s, Sproul engaged in polemics to defend the evangelical doctrine of justification by faith alone. He has been described as "the greatest and most influential proponent of the recovery of Reformed theology in the last century."

Sproul was born in Pittsburgh, Pennsylvania, as the second child of Robert Cecil Sproul, an accountant and future veteran of World War II, and his wife, Mayre Ann Sproul (née Yardis). Sproul was baptized as a boy at Mount Washington Methodist Church. His family later joined Pleasant Hills Community Church, a congregation of the United Presbyterian Church. He was an avid supporter of the Pittsburgh Steelers and Pittsburgh Pirates as a youth, and at the age of 15, he had to drop out from high school athletics in order to support his family.

Having become a Christian in 1957, Sproul met with his childhood minister to share his conversion. During the meeting, the minister stated, "If you believe in the resurrection of Christ, you're a damn fool!" stunning Sproul, left wrestling with "feelings of betrayal."

Proceeding with study, he obtained degrees from Westminster College, Pennsylvania (BA, 1961), Pittsburgh Theological Seminary (MDiv, 1964), the Vrije Universiteit Amsterdam (Drs., 1969), and Whitefield Theological Seminary (PhD, 2001). He taught at numerous colleges and seminaries, including Reformed Theological Seminary in Orlando and in Jackson, Mississippi, and Knox Theological Seminary in Ft. Lauderdale.

One of Sproul's mentors was John H. Gerstner, being one of his professors at Pittsburgh-Xenia Theological Seminary. The two of them, along with Arthur Lindsley, another of Gerstner's students, co-authored the book Classical Apologetics in 1984. Sproul's ministry, Ligonier Ministries, made recordings of Gerstner teaching various courses on theology and the Bible. John M. Frame records that Gerstner was Sproul's "main intellectual influence."

Sproul recalls encountering theological opposition inside a liberal environment during his early studies:

When I was a seminary student ... I was selected to preach the senior sermon before the whole student body, the whole faculty, and also the presbytery who met there that day. And I preached that day on sin, and I made reference to some of the definitions of sin that we had learned at seminary: that sin, you know, was existential, inauthentic existence, or sin was some kind of neurosis ... And I said, you know, we may be neurotic, and we may be doing everything that we know how to destroy what authenticity of existence we may have, but ... the meaning of sin, as [Scripture and] our own confession says, is that it's "any want of conformity to, or transgression of, the law of God." ... Well, the student body that was largely liberal ... congratulated me, and they were very positive. I go make my way to the back of the church, and the dean of the institution comes up to me, and he's irate. [He physically threw me up against a wall and accused me of distorting the Bible.] ... So I went straight upstairs to Dr. Gerstner's office, who was my mentor, and I said, Dr. Gerstner, did I distort the truth of God? [I was so upset, I was shaking.] And he looked at me, and he said, ... "Every Christian in heaven from Paul to B. B. Warfield is rejoicing at the sermon that you preached in this house today." ... I was so relieved to hear his evaluation.