Appearance and character -
A tall, beautiful, blonde, white woman in her late 20s, Barbara wears only a man's white shirt and white stiletto shoes.
The only background information we have on Barbara (no last name is used or credited) is she works for the criminal syndicate BIG O and she has killed Tina's partner in a similar fashion prior to to her attempt on Helm's life.
She is obviously a cold blooded killer, a vamp, able to act a part plausibly well, using her seductive charms to put even very experienced agents such as Helm off their guard in order to kill them.
A slim, stiletto style knife. After Barbara's death, Tina takes a gun out of the female assassin's handbag.
The story -
ICE secret agent Matt Helm (Dean Martin) must thwart the plans of the evil organization BIG O, which plans to explode an atomic bomb and start World War 3.
Barbara's role in the plot -
Barbara seduces and then kills ICE operatives who are interfering with BIG O's nefarious schemes. Helm is her latest target.
Barbara pretends to be an ICE operative who has been sent to persuade Helm to undertake a new mission he wants to avoid.
When she first tries to pull her knife on Helm she's behind him. But the ICE agent turns around to face her at that moment, so Barbara is forced to abandon her initial attempt. As she has Helm in her clinches and they kiss, she makes her second try, retrieving the deadly knife hidden in her hair; she is about to plunge it into Helm's back, but Tina (Daliah Lavi), an ICE agent who later turns out to be a traitor, who arrives just in time. Tina fires 2 bullets into the female assassin's own back, killing her.
Viewpoint - Barbara only appears in one sequence of the movie, near the beginning. Her early disappearance deprives the rest of the film of a notable villainess. However, the single scene featuring Kovack's seductively evil Barbara, with her classic, fitting (and fairly graphic) demise, is a favorite among many villainess fans.
- Nancy Kovack appears (with brunette hair) as Sheila Sommers, the ex-girlfriend of Darrin Stephens (Dick York) in two episodes of the TV series "Bewitched" from 1964-1968. As a blonde, she played other villainesses (perhaps being a perfect cast for the trope of the “evil blonde” https://allthetropes.org/wiki/Blondes_Are_Evil),
- Nancy Kovack appeared as Queenie, the Joker's henchwoman in the 1966 episodes "The Joker is Wild" and "Batman is Riled" for the TV series "Batman".
- Nancy Kovack appeared as Sonja, the KAOS agent in the 1969 episode "The Night They Raided Knights" in the TV series Get Smart.