Noun

Singular evil twin

Plural evil twins

evil twin (plural evil twins)

1. (idiomatic) A duplicate or counterpart of something or someone that acts in a contrary, nefarious, or insidious manner.

   As a ploy to discredit the reformist politician, the opposing party had hired a lookalike to act as his evil twin and be seen in a variety of compromising situations.

   • 2003: Peter Halstead, Sea Sun [1]

     ...we see the flip side, the evil twin, the dark side of addition. Human nature contains both a thing and its opposite in varying degrees of tension, and so for every plus there is a minus.

   • 2004: Bob Sullivan, Your Evil Twin: Behind the Identity Theft Epidemic [2]

     ...[he]..lived his life under [another man's name], becoming his evil twin: Staas bought and sold homes, opened bank accounts, obtained credit, married twice, and was arrested at least three times.

2. (networking) A rogue wireless access point installed near a legitimate one for purposes of eavesdropping or phishing.

Synonyms

• (duplicate of contrary or nefarious intent): alter ego, changeling, doppelganger

The evil twin is an antagonist found in many different fictional genres. They are physical copies of protagonists, but with radically inverted moralities. In filmed entertainment, they can have obvious physical differences with the protagonist—such as facial hair, eyepatches, scars or distinctive clothing—that make it easy for the audience to visually identify the two characters. Sometimes, however, the physical differences between the characters will be minimized, so as to confuse the audience. Both roles are almost always played by either the same actor, or (if the actor has one) the actor's actual twin.

Though there may be moral disparity between actual biological twins, the term is more often a misnomer. In many cases, the two look-alikes are not actually twins, but rather physical duplicates produced by other phenomena (e.g. alternate universes). In others, the so-called "evil" twin is more precisely a dual opposite to their "good" counterpart, possessing at least some commonality with the value system of the protagonist.

Origins