I think 'Inferno' by Dan Brown is also quite popular. It involves a conspiracy related to Dante's Inferno and a threat to the world's population. The fast - paced action and the mystery that surrounds the plot make it a hit. Also, 'The Silence of the Lambs' has elements of conspiracy in the sense of the serial killer's motives and the way the FBI tries to uncover the truth. It's a classic that has maintained its popularity over the years.
Among the popular ones is 'The Bourne Identity' series. The main character is on a journey to discover his true identity while uncovering a large - scale conspiracy. The books are full of action, mystery, and international intrigue. The idea of a man with amnesia trying to figure out his past while being hunted is a very appealing and popular concept in the world of conspiracy thriller novels.