The Chanteuse

A stock character in anything even very loosely inspired by Film Noir. Every lounge will have a sultry female singer singing a sultry song. Her favourite outfit is a long evening gown, usually red, slit high up on the leg. If she becomes a named character, she will often be the Veronica in a Betty and Veronica romantic subplot. She could just there in the background because every lounge that has anything approaching a Film Noir feel must have this trope.

She is always surrounded by an air of melancholy. This could be because she herself is melancholy, or because the lonely male hero experiences a connection with her while she is singing but cannot have her. She tends to be out of the main hero's reach perhaps because she is a dangerous Femme Fatale, because she is already involved with someone else (usually a villain), or simply because she is so aloof. This character can be very useful for highlighting a feeling of loneliness, because her sultry songs will often create a feeling of a connection between the singer and the listener, but circumstances will prevent that feeling from becoming a true connection. For that reason, this trope is a favourite of Film Noir, a genre that thrives on a feeling of melancholy and stoic loneliness.

This character may frequently be seen Sitting Sexy on a Piano. Compare Glamorous Wartime Singer.

Examples of The Chanteuse include:

Film

Jessica Rabbit in Who Framed Roger Rabbit?.
Tallulah in Bugsy Malone.
Emma in Dark City.
Tina in The Mask.
Lil Sheridan (Marilu Henner) in Johnny Dangerously.
Uschi, the heroine of Der Schuh des Manitu, is introduced that way. The film doesn't have anything to do with the Film Noir, though; it's just Troperiffic.
Cast a Deadly Spell. When we first see Connie Stone (Julianne Moore), she's singing a song in Harry Bordon's nightclub. You can watch her performance here.
Michelle Pfeiffer from The Fabulous Baker Boys.
- The movie's Sitting Sexy on a Piano scene is parodied in Hot Shots.
The singer at the Blue Note in Naked Gun 2½: The Smell of Fear played by singer Colleen Fitzpatrick a.k.a. Vitamin C.
Envy Adams from Scott Pilgrim vs. the World fits the criteria, despite not being Film Noir.
Gina in Porco Rosso.
Sugar Kane in Some Like It Hot, played by Marilyn Monroe. Again, this is a comedy, not film noir per se.
The 1990 Dick Tracy movie had Breathless Mahoney, classic nightclub Femme Fatale played by no one less than Madonna. Her performance of "Sooner or Later (I Always Get My Man)" actually won an Academy Award.
Isabella Rossellini in Blue Velvet.
Ellen Aim in Streets of Fire.

Live Action TV

Star Trek: Voyager. Seven of Nine was made one in a holoprogram set in German-occupied France.
- And in Star Trek: Deep Space Nine, Odo was coached in flirting by Vic Fontaine, who created for this purpose a holo-version of Kira, who fulfilled this trope. She was in the end swapped for the real Kira.
Jan Levinson makes a cameo appearance as one of these in The Office (US) episode "Threat Level Midnight" movie-within-a-movie possibly a nod to Melora Hardin's cameo as one in The Rocketeer (or maybe simply because she can sing).
The season six opener of NCIS had Ziva David playing this part very well, with the actress Cote de Pablo actually doing her own singing. Then someone rudely left a bomb behind. (What, this is NCIS, you know!)

Newspaper Comics

Burma in Terry and the Pirates (it was her original career).

Theatre

City of Angels has Bobbi as this stock Film Noir character. Her number, "With Every Breath I Take," is a slow minor-key torch song.
In Follies, Sally takes on this look for her Loveland number, "Losing My Mind".

Video Games

The unnamed background version of this trope appears in the game Alice Is Dead. She sings a song that is a mixture of Wonderland surrealism and an attempt to seduce the listener.
Carol MacLaine in Deadly Premonition.
Julia Heartilly from the flashback sequences of Final Fantasy VIII
Olivia Ofrenda in Grim Fandango

Western Animation

The unnamed singer who performs "Betcha Neva" in the Iceberg Lounge in Batman: Mystery of the Batwoman.
Red from Red Hot Riding Hood and other Tex Avery shorts.
Miss Kitty Mouse from The Great Mouse Detective.
The "Queen Hornet" episode of Dynomutt Dog Wonder features one, who sings the theme song from Jabberjaw.