Vernita Green.

Appearance
Vernita is an attractive African American woman of average height (around 5'7"), with a slim but athletic and toned figure (clearly showing she maintains a regular workout routine). She has mocha-colored skin, dark brown eyes, and full lips (often with beige or natural lipstick). She wears her long hair in cornrows (when she appears in the film). In the fight scene, she wears comfortable loungewear, but her agility and strength are evident.

Personality
Vernita is pragmatic, cunning, and fiercely protective of her family (especially her daughter Nikki). She displays a calculating and treacherous side: she tries to avoid combat by talking and negotiating with the Bride, but she doesn't hesitate to ambush her with a hidden weapon when she sees an opportunity.
Despite her "normal" life, she retains her killer mentality: cold under pressure, an expert in hand-to-hand combat, and especially skilled with knives. There is an implicit mutual professional respect between her and the Bride (both recognize each other's skill). She also harbors a touch of resentment and envy, as seen in her famous final line:
"Black Mamba... I shoulda been muthafuckin' Black Mamba."
(He complains that he was given the codename Copperhead instead of the one he considered more prestigious).

Trivia

His codename Copperhead refers to a venomous snake (copperhead) that is an ambush predator and prefers to avoid humans if possible → it represents his fighting style and his attempt to avoid direct confrontation.

•The alias Jeannie Bell is a tribute to the 70s exploitation actress Jeannie Bell (known for blaxploitation films such as TNT Jackson).

•Originally his codename was going to be Cobra, but Tarantino changed it to Copperhead.
His final line ("I shoulda been muthafuckin' Black Mamba") is one of the most remembered and quoted from the film.

•The scene of his death and the Bride's speech to Nikki ("When you grow up, if you want revenge…") is a parallel with a scene from the movie The Punisher (1989).
The gun he uses to try to kill the Bride is hidden in a Kaboom cereal box (a typical Tarantino humor reference).

•In Kill Bill: Volume 2, Bill mentions that Nikki might one day seek revenge against the Bride for killing her mother (an idea that Tarantino has mentioned for a possible Vol. 3).

Vernita Green (also known as Copperhead or by her alias Jeannie Bell) is one of the characters in Kill Bill: Volume 1 (2003), directed by Quentin Tarantino. She is portrayed by Vivica A. Fox.

Biography
Vernita Green was a professional assassin and a member of the Deadly Viper Assassination Squad (DiVAS), the elite squad led by Bill. She participated in the Two Pines Massacre, where she and the rest of the team murdered almost everyone present at Beatrix Kiddo's (the Bride's) wedding rehearsal, leaving her in a coma.

Four years later, Vernita abandoned her life as an assassin, retired, and constructed a new identity. She married a doctor named Lawrence Bell, had a young daughter named Nikki (Nikkia Bell), and lived a seemingly normal life as a housewife in a suburb of Pasadena, California, under the alias Jeannie Bell.

She is second on the Bride's Death List Five (though the first to die in the film). She dies in a brutal knife fight in her own home, after trying to trick the Bride by shooting her with a gun hidden in a Kaboom cereal box.