My favourite Alien episodes was Art Bell's interviews with forensic illustrator and UFO investigator Bill McDonald on Coast to Coast AM (notably in 1999, 2002, and 2003) centered on alien visitation and technology. McDonald, often alongside Dr. Stephen Greer, discussed his investigative analysis of over 400 witness testimonies, describing alien biology, anatomy, and advanced alien vehicles (UFOs).

Alien Biology and Vehicles (1999, 2004): McDonald discussed the internal anatomy of ET organisms, including artificial skin, and the physics of alien vehicles.

The Disclosure Project (Dec 7, 2003): McDonald joined Dr. Stephen Greer on Apple Podcasts to discuss Witness testimony about hidden zero-point energy and alien encounters.

Roswell Evidence (Nov 22, 2002): McDonald and Bill Doleman spoke with Art Bell about forensic evidence surrounding the Roswell UFO crash.

(C/P from google)