In this retrospective countdown episode, Giorgio Tsoukalos revisits ten creatures previously featured on Ancient Aliens that theorists believe could provide evidence of extraterrestrial visitation. The episode begins with Bigfoot at number ten, citing a 1979 encounter by author Chris O'Brien on Mount Shasta in northern California, where he heard terrifying vocalizations in dense forest. Ancient astronaut theorists point to alleged correlations between Bigfoot sightings and UFO activity—particularly a wave of reports in Pennsylvania where witnesses claimed to see ape-like creatures emerging from wooded areas during periods of increased UFO sightings. Most provocatively, the episode presents a secondhand account from Montana where a rancher allegedly shot at a Sasquatch with a .30-06 rifle, only to have the creature "disappear in a flash of light," which theorists interpret as possible evidence of interdimensional or extraterrestrial technology.
Anthropologist Jeff Meldrum, who maintains a collection of over 200 footprint casts, suggests there may be a biological species behind Bigfoot legends, though he approaches the question from a zoological rather than extraterrestrial perspective. Mainstream science notes that despite thousands of reported sightings, no physical evidence—bodies, bones, or verifiable DNA—has confirmed Bigfoot's existence, and many alleged encounters lack corroborating witnesses or documentation. For curious viewers, the episode offers an intriguing catalog of folklore and eyewitness testimony that raises questions about how cultures interpret unexplained experiences, even if the extraterrestrial connection remains speculative.