I stumbled upon a Wikipedia entry for this and was interested.
Apparently, comic book readers refer to the countless horrors suffered by female associates of superheroes as the Girlfriend-in-the-Refrigerator Syndrome. The term comes from a relatively recent Green Lantern plotline in which Kyle Rayner's girlfriend, Alex DeWitt, is murdered by a villain, hacked to pieces and put in Rayner's refrigerator to be found when he comes home from his Green Latneran duties. Since then, comic nerds have retroactively used the term to describe previous acts of misogyny — any time a female character exists as a helpless victim who dies in order to make the hero sad.
Like Gwen Stacy, Peter Parker's first girlfriend, whose neck is snapped when the Green Goblin tosses her form Queensboro Bridge and Spider-Man snags her with his webbing too sharply.
Like Karen Page, secretary to Daredevil's alterego, Matt Murdoch. She becomes Murdoch's sweetheart, then a heroin addict, then a porn star, then a prostitute. Eventually Karen sells out Daredevil's true identity, but he forgives her and she cleans up her life. Whoops. No. Then she gets assassinated.
Or even Barbara Gordon. She's Batgirl until the Joker learns her true identity, puts a bullet in her spine, then rapes her, all to get at Batman.
This kind of horrible thing happens a lot, though recent sentiment is pressuring writers to avoid it. From a literary standpoint, it's interesting as all fuck-out — not only that it exists, but also that they have a name for it.