"[5] To further develop the Villanelle character for television, Waller-Bridge applied her impressions from her interview of Angela Simpson, an Arizona woman who had imprisoned, tortured and murdered a victim, and who—though affectless during the interview—afterward erupted with exuberant, giddy pride at her own performance.

[7] Bradbeer also applied his appreciation of the Coen brothers' characteristic blend of comedy and terror, crafting characters who are most chilling when behaving almost normally and who are most dangerous when acting happy, innocent, playful and naughty.

[9][10] In The New Yorker, Jia Tolentino likened the entire Killing Eve series to the villanelle poetic form, writing that the show is about the "iteration of a recognizable pattern, its pleasures emerging in the internal twists".

[10] Villanelle is a brutal hired assassin who soon becomes involved in a cat-and-mouse game with MI5 intelligence operative Eve Polastri (Sandra Oh), the two women becoming mutually obsessed[14] and sharing what has been called a "crackling chemistry... between bitter enemies and would-be lovers".

[4] Agent Polastri tracks the "utterly unforgivable" assassin Villanelle across Europe, not as hero and villain but as "two broken women whose flaws bind them together in a twisted pas de deux.

"[15] As the series progresses, Villanelle's backstory is revealed: she is an orphan with a violent reputation, who once developed an obsession for a nurturing older language teacher named Anna (Susan Lynch), with whom she had an affair.

[4] Not simply a hired assassin, Villanelle was described as "taking joy in the pain of others" and having "no moral fetters holding her back", having been "raised to kill without guilt or concern, ... love or loyalty".

[17] Though Villanelle's competence is "frightening" and "exaggerated", Jia Tolentino wrote in The New Yorker that she is "essentially a child, petulant and silly and rude", but whose "theatrical instincts flare back to life" in a deadly situation.

[11] Tolentino also inferred that Villanelle may be "unravelling" or replaying childhood events: demanding her handler admit he loves her more than his daughter; having lost her mother early and now looking for an older woman for mutual care and devotion; seeking praise for her brilliant performance.

[24] Though she "acts as televisual wish fulfillment, a touching melancholy comes to the surface ... suggesting that (she) doesn't consume with such hearty gusto out of a simple lust for life but from a need to fill the void inside her".

Waller-Bridge endorsed that "Villanelle does have fun, choosing to only do things that might bring her joy"—from selecting haute couture to contriving murder techniques—a fearlessness that is a perfect counterpoint to the self-consciousness and guilt that cripples Eve in the first season.

[27] Hanh Nguyen commented in IndieWire that Villanelle "can only mimic the actions of others in hopes to achieve the same result", though noting that "psychopaths–and especially Villanelle–are able to draw people in through the sheer force of their confidence and personality".

[14] McFarland noted Villanelle's killing patterns and called the show "perfect for the #MeToo era," writing that it "slakes one's desire to see piggish misogynists get what's coming to them".

[14] However, writing in The Atlantic, Hannah Giorgis asserted that a feminist, political focus overlooks important thematic and aesthetic components: Villanelle subverts feminine stereotypes so as to "carve a jagged space into the serial-killer canon".

[15] In accord, Willa Paskin wrote in Slate that "the disfigured, beating heart of Killing Eve is the way that Villanelle's gender and manner, her very femininity, keep our acculturated brains from being appropriately terrified of her.

"[21] Describing how Villanelle "does what she always does: exploit society’s misogyny by imitating a victim of it", Emily Nussbaum wrote in The New Yorker that the potent idea that undergirds the show is that "femininity is itself a sort of sociopathy, whose performance, if you truly nail it, might be the source of ultimate power".

[21] In The Irish Times, Peter Crawley characterised Comer's Villanelle as "a young woman with an angelic face and a devil's stare", adding that she embodies "a pleasing paradox: a phantom who craves recognition".

[34] In May 2019, Hanh Nguyen wrote in IndieWire that Villanelle's ability "to shift from seemingly caring to cold and calculated in one breath as a reaction to how events change around her" is chilling, but Comer makes the transformation believable.