In the United States, a credit zombie is a person who has been erroneously declared dead by the Social Security Administration by being listed in its Death Master File (commercially known as the Social Security Death Index). It is unclear why living people are added to this list. The term "credit zombie" is an analogy to the concept of the zombie being a person who was once alive walking around as an animated corpse after death. A credit zombie is someone who is officially dead, while it is obvious that person is actually alive.