Doppelgänger

"If you travel far enough, you will eventually meet yourself."

– Jean-Luc Picard, 2365 ("Time Squared")

Doppelgänger was a word from the German language which meant an exact duplicate of a living person. The term doppelganger has been used throughout history, most often when someone met an identical copy of themselves who was not a biological twin. Miles O'Brien, Harry Kim, Naomi Wildman, and Kes were replaced by doppelgängers of their respective "originals" after they died. (DS9: "Visionary", VOY: "Deadlock", "Fury")

Doppelgängers

Bioreplicants: Clones • Golems • Replicants • Spatial scissions • Transporter duplicates

Shapeshifters: Allasomorphs • Biomimetic lifeforms • Cellular metamorphosis • Chameloids • Changelings • Coalescent organisms • Harvongians • Mimetic simbiots • Vendorians

Holographic duplicates

Illusory people

Physical duplicates[]

Travis Mayweather[]

In 2152, the automated repair station created a duplicate of Travis Mayweather who was subsequently electrocuted. He was mistaken for Mayweather until Doctor Phlox performed an autopsy. (ENT: "Dead Stop")

James T. Kirk[]

In 2266, a transporter accident split James T. Kirk into separate "good" and "evil" personas. It was eventually discovered that the two could not live without each other, and they were reintegrated by the transporter. (TOS: "The Enemy Within")
Later in 2266, Kirk was again duplicated, this time in the form of an android, by Roger Korby and other androids on the planet Exo III. This duplicate was vaporized by Andrea, who mistook it for the real Kirk. (TOS: "What Are Little Girls Made Of?")

Spock[]

In 2269, a giant clone of Spock was created by Stavos Keniclius 5 and christened Spock Two. When the original Spock departed the planet Phylos, Spock Two remained behind to work with Keniclius to work on a cure for a plague afflicting the Phylosians. (TAS: "The Infinite Vulcan")

Stavos Keniclius[]

Stavos Keniclius cloned himself several times in an attempt to find the perfect specimen to create a clone peacekeeping force. (TAS: "The Infinite Vulcan")

Jean-Luc Picard[]

In 2365, the USS Enterprise-D encountered a Jean-Luc Picard from six hours into the future. This Picard was killed by the current Picard, and then vanished. (TNG: "Time Squared")
In 2366, Picard was replaced by an alien replica; upon returning to the Enterprise-D, the real Picard commented that he "hoped his doppelgänger hadn't caused too much trouble." (TNG: "Allegiance")
Sometime in the 2360s, the Romulans created a clone of Picard as part of a plot to replace him. This clone, using the name Shinzon, eventually became the Praetor of the Romulan Star Empire before being killed by Picard in 2379. (Star Trek Nemesis)
In 2399, the memories of Jean-Luc Picard were transfered into a golem, shortly before the original's death. This new body was identical apart from a defect in the parietal lobe, which caused Picard's Human body to fail. (PIC: "Et in Arcadia Ego, Part 2")

William T. Riker[]

In 2361, a transporter accident on Nervala IV duplicated William T. Riker, stranding one on the surface while the other left with the USS Potemkin. Eight years later in 2369, the Enterprise-D returned to Nervala IV and found and rescued "Thomas Riker". (TNG: "Second Chances")

Because the split between signals resulted in an equal distribution of Riker's transporter pattern, both of them had an equally legitimate claim to being the "real" William T. Riker, however it can be argued that "Thomas" is the real Riker as the transporter chief aboard the Potemkin used a second beam signal to retrieve the current person known as William T. Riker while the original beam signal rematerialized on the planet surface.

In 2365, the Mariposans stole Riker's DNA and created a clone from it. This clone was killed by the original Riker. (TNG: "Up The Long Ladder")

Katherine Pulaski[]

In 2365, the Mariposans stole Dr. Pulaski's DNA and created a clone from it. This clone was killed by the original Pulaski. (TNG: "Up The Long Ladder")

Miles O'Brien[]

Miles O'Brien was killed in 2371, after becoming infected with delta-series radioisotopes following an accident aboard Deep Space 9. He was replaced by his future self from a few hours later, making the current O'Brien a doppelgänger of the "original." (DS9: "Visionary")
A replicant of O'Brien was created by the Parada government, possibly to assassinate someone at the upcoming peace talks on the station between the government and rebel forces. This O'Brien died never knowing he wasn't the "real" one. (DS9: "Whispers")

B'Elanna Torres[]

In 2371, the Vidiian Sulan used a genotron to extract B'Elanna Torres' Klingon DNA, leaving her fully Human, and then reconstitute a fully Klingon version of her. The Doctor was able to reintegrate Torres' Klingon DNA into her Human self after her Klingon half was killed escaping the Vidiians. (VOY: "Faces")

USS Voyager[]

The entirety of the USS Voyager (with the exception of its antimatter supply) was duplicated by a spatial scission in 2372. One of the Voyagers self-destructed to destroy a Vidiian ship attacking them, while the other continued on its way, albeit heavily damaged. (VOY: "Deadlock")

Harry Kim[]

Harry Kim was killed on Voyager when he was pulled through a hull breach on deck 15. He was replaced by the other Harry Kim from the other Voyager, making the current Harry a doppelgänger of the original. (VOY: "Deadlock")

Naomi Wildman[]

Naomi Wildman died of complications due to hemocythemia. She was replaced by the Naomi Wildman for the other Voyager, making the current Naomi a doppelgänger of the original. (VOY: "Deadlock")

Kes[]

In 2376, Kes time traveled to 2371, so she could return her with past self to Ocampa while Voyager's crew would by handed over to the Vidiians. The attempt failed, and Janeway was forced to kill the older Kes. Her actions warned Janeway of the future, allowing her to prevent the future the older Kes came from. By 2376, when Kes repeated the actions of her deceased counterpart, up to the point of time traveling, Janeway was able to convince her not to time travel, with the "past" Kes opting instead to return to her homeworld. (VOY: "Fury")

Iliana Ghemor[]

(DS9: "Second Skin")

Shapeshifters[]

Cellular metamorphosis[]

See: Cellular metamorphosis (TOS: "Whom Gods Destroy")

Chameloids[]

A chameloid impersonated captain James T. Kirk during his imprisonment on Rura Penthe. (Star Trek VI: The Undiscovered Country)

Changelings[]

Changelings replaced, or impersonated, a number of individuals in the years leading up to, and during, the Dominion War. (Star Trek: Deep Space Nine)