Kerrigan first appears in StarCraft as a twenty-six-year-old Ghost, a psychic trained both physically and mentally as an expert espionage agent and assassin.

[8] Tricia Helfer replaced her, voicing Kerrigan in StarCraft II: Wings of Liberty as well as the expansions Heart of the Swarm and Legacy of the Void.

[11] Having been conscripted into the Confederate Ghost program as a child due to her psychic potential, Kerrigan is described in the manual for StarCraft as never having been given the chance for a normal life.

[12] However, after her transformation by the Zerg, Kerrigan is freed from her inhibitions—as well as her neural conditioning—and indulges her darker traits (though Heart of the Swarm implies that at least part of her villainy was due to the influence of a fallen Xel'naga named Amon).

A hint of her former moral sensitivity is to be noted when towards the end of the Zerg campaign of Brood War, she states how she feels weary of slaughter for the first time since her transformation.

Kerrigan has also become far more physically aggressive, relishing close quarters combat so much that at one point in the novel Queen of Blades, she begins absent-mindedly licking the blood of her victims from her fingers.

[14] Prior to her infestation, Kerrigan is described as being a graceful and deadly woman, exceedingly agile and athletic,[15] possessing jade-green eyes and brilliant red hair usually worn as a ponytail.

[17] Kerrigan is rarely seen out of her armor, a form-fitting hostile environment suit specifically designed for Ghost operatives and equipped with a personal cloaking device.

Despite maintaining her stature, build, and facial features, she is described in Queen of Blades as having mottled green skin, covered in a glossy protective carapace.

Kerrigan's eyes are bright yellow as opposed to her natural green, and her hair has transformed into stalks, described as being segmented like an insect's legs.

Her physique resembles that of her human form, though her skin turns a metallic gold color with flames along the surface, and she has a pair of angelic wings.

The Overmind immediately launches the bulk of the Zerg Swarm to invade the planet, although Kerrigan remains behind on Char to hunt down Tassadar and Zeratul.

She also gains an ally in Samir Duran, an apparently infested ex-Confederate Ghost who infiltrates the newly arrived forces of the United Earth Directorate (UED), and attempts to sabotage their mission to enslave the Zerg.

At BlizzCon 2007, Chris Metzen explained that in the years after Brood War, Kerrigan relocated to Char, pulling back most of the Zerg, and has since been quiet.

At one point, Zeratul suddenly appears on board Raynor's ship, allowing him to discover an ancient Xel'naga prophecy that Kerrigan must live as she will save the universe from a coming war against Protoss-Zerg hybrids.

After learning this, Raynor mounts an invasion on Char in collaboration with Dominion forces under the control of Valerian, to eliminate the Zerg and rescue Kerrigan.

[30] After regaining her human form, Kerrigan is brought by Raynor to a secret research facility run by Valerian Mengsk to determine if she can still control the Zerg.

Mengsk's publicly announces he has executed Raynor, and while planning to enact revenge against him, Kerrigan is approached by Zeratul, who tells her to travel to Zerus, the original homeworld of the Zerg.

Kerrigan chooses to increase her power by entering a chrysalis, transforming again into a Zerg and Terran hybrid, though this time retaining her original personality.

[31][32] During the events of Legacy of the Void, Kerrigan enters into an alliance with Artanis while investigating the Xel'Naga "homeworld" Ulnar, which the pair discover is in fact a colossal space station.

The novel Uprising portrays Kerrigan's training as a Ghost assassin from an early age, where she is subjected to intense psychological abuse from her Confederate trainer, Lieutenant Rumm.

After sensing a nexus of joined human minds caused by protagonist Jake Ramsey at the end of the first novel, Kerrigan sends Zerg forces to its location, infesting the half-dead body of a Dominion-funded black marketeer, Ethan Stewart.

[41] Her transition from Terran to Zerg was particularly praised,[42] and they opined that the reason her face appeared on the box art for Brood War was due to how recognizable she had become.

[41] Following her appearance in Brood War, IGN commented favorably on the evolution of Kerrigan's character through StarCraft's storyline,[43] and also described her as one of the most memorable villains in gaming.

[45] Following her appearance in StarCraft II and its expansions, numerous video-game journalists described Kerrigan among the best villains in gaming,[46][47][48][49][50][51] with many commenting on the complexity of her character.

"[47] Rich Antoniello from Complex's described her life as a "tragic tale of nearly Shakespearean proportions",[49] and Hanuman Welch considered her the most evil woman in video gaming.

He criticized her over-sexualization, such as her exaggerated hip swing when walking and her feet resembling stiletto heels, which he argued is impractical for her frequent close combat fights and was only added to be visually appealing for male viewers.

However, Blomquist also comments on Kerigan subverting hetero-normative gender roles, such as by penetrating Mengsk, the patriarchal Terran leader, with her skeletal wings before killing him, and also considers her sardonically referring to herself as "Queen Bitch of the Universe" as an empowering reclamation of the term 'bitch'.

[60] In 2012, Dutch musician Maduk and Canadian singer Veela released the song Ghost Assassin, a dedicated anthem for Kerrigan's arc throughout the StarCraft franchise.