William Gurnall (1616–1679) was an English pastor and author, remembered primarily for his influential book The Christian in Complete Armour, a series of sermons based on Ephesians 6 about spiritual warfare. He studied at Emmanuel College, Cambridge, and became the rector of Lavenham, Suffolk, where he served faithfully for many years. Gurnall was committed to the Church of England during a time of great religious turmoil and managed to retain his post through the English Civil War and Restoration. His writings continue to be valued for their theological depth and practical encouragement for Christian living.