Dive into the shadowy world of "conspiracy" theories! From the enduring mysteries of MKUltra and the alleged secrets of Denver International Airport to the bizarre claims about Avril Lavigne's replacement and Ted Cruz being the Zodiac Killer, this list ranks some of the most talked-about and outlandish theories. Explore beliefs ranging from the existence of Cryptids and Reptile Overlords to the persistent questions surrounding JFK's assassination and the events of 9/11. Are aliens visiting us? Is the moon landing a hoax? Prepare to question everything you thought you knew as we sort the "believable" from the utterly unbelievable.