Usually refers to the act of
abducting a person and replacing him or her with an identical
doppleganger, the ultimate goal being the creation of a race of
pod people.
Popularized by the film
Invasion of the Body Snatchers in
1956, the concept originated from the
novel by author
Jack Finney. The main signs of body snatching are
out of character behavior and lack of
emotion; also, the presence of
alien seed pods is a
dead giveaway.
See also:
Robert A. Heinlein's
The Puppet Masters. Similar to
zombification, minus
bits falling off.