A look-alike, or double, is a person who bears a strong physical resemblance to another person, excluding cases like twins and other instances of family resemblance.
Some look-alikes have been notable individuals in their own right. Other notable look-alikes have been notable solely for resembling well-known individuals, such as Clifton James, who acted as a double for British Field Marshal Bernard Montgomery during World War II.
A political decoy is a person employed to impersonate a politician, to draw attention away from the real person or to take risks on that person's behalf. This can also apply to military figures, or civilians impersonated for political or espionage purposes.
The political decoy is an individual who has been selected because of a strong physical resemblance to the person being impersonated. This resemblance can be strengthened by plastic surgery. Often, such decoys are trained to speak and behave like the "target".
Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ('non-identical' or 'fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. Since identical twins develop from one zygote, they will share the same sex, while fraternal twins may or may not. In very rare cases, fraternal or (semi-) identical twins can have the same mother and different fathers (heteropaternal superfecundation).
In contrast, a fetus that develops alone in the womb (the much more common case in humans) is a singleton; one of a multiple birth is a multiple. Unrelated look-alikes whose resemblance parallels that of twins are referred to as doppelgänger.
Amphitryon is a French language comedy in a prologue and 3 Acts by Molière which is based on the story of the Greek mythological character Amphitryon as told by Plautus in his play from ca. 190–185 B.C. The play was first performed at the Théâtre du Palais-Royal in Paris on 13 January 1668. A whiff of scandal surrounded the play, with some claiming that Molière was criticizing the amorous affairs of Louis XIV of France in the guise of Jupiter. It was performed again three days later at the Tuileries Garden in the presence of Louis XIV.
Amphitryon was an immediate success with the French aristocracy and the play was performed a total of 29 times by Easter 1668. The popularity of the work was such that one of the names of the characters became a part of the everyday French language. The word 'Sosie' in French now means look-alike, a reflection of the events in the play where the character Sosie (a part which was portrayed by Molière himself in the comedy's first production) is a doppelgänger of the God Mercury.