Dead Herring

There are movers and shakers in stories, they're called Heroes and villains. Everyone else is more or less an Innocent Bystander to these two people or factions. They are characters whose sole plot-critical function is to have stuff happen to them; the plot would be no different had they never existed, except that the Hero's heroism, the Villain's villainy and the dangers facing the main character just wouldn't be as powerful without someone to use as a punching bag. Essentially, they are a Red Herring used to prove a point, by dying if necessary.

As such they are storytelling tools, and this Super-Trope categorizes their use based on type: demonstrating danger; causing an emotional reaction in the hero, the viewer or both, and even as a source of humor.

Type I: Their death is not necessarily intended to evoke emotion, just demonstrate the danger.

 * Cannon Fodder
 * Dead Serious
 * Disposable Sex Worker
 * Mooks
 * New Meat
 * Red Shirt
 * Redshirt Army
 * Red Shirt Reporter
 * Sacrificial Lamb

Type II: Their death is intended to evoke great emotion in another character, usually a protagonist.

 * Dead Little Sister
 * Dead Partner
 * Dead Sidekick
 * Death by Newbery Medal
 * Death By Origin Story
 * Deceased Parents Are the Best
 * Disposable Woman
 * Forgotten Fallen Friend (a subversion; after accepting The Call, the Heroes feel little for the death of their comrade.)
 * Friendly Target
 * I Let Gwen Stacy Die (cross-pollination with Type I, although it is the emotion generated which shows the danger.)
 * The Lost Lenore
 * Sacrificial Lion
 * Stuffed Into the Fridge
 * They Were Holding You Back

Type III: Their death is intended to evoke emotion in the audience, but may mean little to the other characters.

 * Decoy Protagonist
 * Mauve Shirt
 * Player Punch

Type IV: Their suffering is intended to evoke humor. They are unlikely to die.

 * Butt Monkey
 * The Chew Toy
 * Cosmic Plaything
 * The Eeyore

Type V: Their suffering evokes sympathy from the audience.

 * The Woobie
 * Slave Mooks

Related Tropes:

 * Sorting Algorithm of Mortality
 * We Have Reserves