Alien implants is a term used in Ufology to describe a physical object placed in someone's body after they have been abducted by aliens. Claimed abilities of the implants range from telepresence to mind control to biotelemetry (the latter akin to humans tagging wild animals for study). As with UFO subjects in general, the idea of "alien implants" has seen very little attention from mainstream scientists because of a lack of verifiable evidence.

According to researcher Peter Rogerson (who is generally skeptical of alien abduction claims), the idea of allegedly genuine alien implants can be traced back to the 1950s, as part of the so-called "Shaver Mystery" -- claims that the "Dero", a sinister civilization beneath the earth, was kidnapping people for torture. Rogerson writes:

... The March 1957 edition of the Long John Nebel radio show featured John Robinson, a sidekick of Jim Moseley reporting a dramatically spooky, if not very plausible, abduction tale. The gist of it was that in 1944 Robinson had a neighbor named Steve Brodie who one day saw (in Robinson's apartment) a copy of one of Ray Palmer's magazines featuring the Dero. Brodie yelled out "He speaks of the Dero!", and proceeded to tell Robinson how he had been prospecting out west with a companion in 1938. One day they encountered two mysterious cowled figures who paralyzed Brodie by pointing a rod-like device at him. When the companion tried to flee, they fired at him and Brodie heard him scream, and smelled burnt flesh. When one of the figures placed 'small earphones' behind his ears he lost consciousness. From time to time he came to, in a place which fellow prisoners told him was the cave of the Dero. Each time his brain began to clear, the cowled one adjusted the earphones and he lost consciousness again.

He eventually came to, walking the streets of Manhattan two years later. Brodie showed Robinson scarred patches behind his ears, a little smaller than a silver dollar. Since his ordeal Brodie claimed he was unable to eat meat ... Time passed; Robinson left the apartment but on returning for a visit found that Brodie had disappeared. Another neighbor told Robinson that he had seen Brodie in Arizona, wandering about like a zombie. We are presumably supposed to conclude that he was back under the control of the Dero.

It is in this unlikely tale that we first encounter the implants (behind the ears, as in Invasion of the Martians) and other abductionist staples such as the paralyzing rods and the doorway amnesia.

Alien implants have featured in fictionalized treatments of the alien abduction scenario, such as in the popular 1990s television program The X-Files and an episode of the ABC comedy drama Castle. A third-season episode of House, M.D. featured an object that Chase believed to be an alien implant in a patient's neck, but turned out to be a fragment of a medical pin.