Pack-rape

Pack-rape, also known as gang-rape, is rape with lots of assailants and a significantly smaller number of victims (usually only one.) Particularly horrific, since there's very little the victim can do about it (a competent fighter could be able to fight off an assailant if not somehow restrained or disabled, but several assailants could easily overwhelm anyone without superpowers that involve becoming intangible or effectively nuking everyone in the immediate vicinity to death). Not something most people want to read about, but inexplicably used as a plot device and an excuse for hurt/comfort. Usually dealt with by either the Department of Bad Slash or the Disturbing Acts of Violence Department, or both. Tends to result in Agents throwing themselves in the Fountain of Bleepka for a few days afterwards.

Examples
 * Violation of the Evenstar
 * Celebrían (badfic)
 * That Series contains at least two examples; Pikkle and Mara are both raped by most of the Corpsemakers horde (mercifully, the author doesn't detail all four thousand of them), and Grath suffers a similar experience in the Monitor barracks.
 * On occasion, this topic can be handled reasonably tastefully, almost invariably when it is non-graphic. For example, this is the fate which awaited Agent Stormsong in his home fic -- the scene was non-graphic, and intended to horrify rather than titillate, so it counts as a good handling of the subject. Even if the characters involved were cute fuzzy animals, because this one was meant to be disturbing.