Richard J. Foster is an American theologian, pastor, and author rooted in the Quaker tradition. Born in New Mexico in 1942, he has served as a minister and professor of theology, focusing primarily on Christian spiritual formation and practice. He is widely known for his influential contributions to Christian literature, encouraging believers to pursue a deeper spiritual life through traditional disciplines.

Foster is the author of several notable works, including the bestselling classic Celebration of Discipline, the exploration of Christian spirituality Streams of Living Water, and the ethical guide Money, Sex and Power. He also contributed to Spiritual Classics, helping readers engage with centuries of devotional writing.