Screwtape is the demon who writes the letters in C.S. Lewis’s 1942 novel.
The Screwtape Letters is structured as a series of 31 letters from Screwtape, a senior demon, to his inexperienced nephew Wormwood. Screwtape advises Wormwood on tempting a human patient away from Christian belief and moral action. Lewis presents the advice ironically, allowing readers to recognize the distortions in demonic reasoning.
The book was published in 1942 by Geoffrey Bles. It began as pieces written for the Anglican newspaper The Guardian, which published the letters during the Second World War. Lewis later collected them into book form and added a preface explaining the unusual method.
Wormwood is therefore not the letter writer but the junior demon receiving the advice. Slubgob is another demon mentioned in the book, while Triptweeze appears in Lewis’s later Screwtape-related material. These names can be confused because the story is entirely framed through correspondence among demons.