6. The Descent - Sarah (Shauna MacDonald)
This is another of our more tragic entries on the list, as Neil Marshall's 2005 horror masterpiece opens in a devastating fashion, with Shauna MacDonald's extreme sports enthusiast losing her husband and daughter in a horrific road accident. Picking up a year later, she and her friends head out on a caving expedition in the hopes of helping her move on - but things go badly wrong, and they soon find themselves lost miles underground with some rather terrifying subterranean flesh-eating humanoids for company. As much as it's a hard-edged survivalist horror and monster movie, The Descent is also a chronicle of a grieving mother's struggle to deal with her loss. Sarah's sanity is already hanging on by a loose thread - but even so, once things go from bad to worse and it turns into a full-on fight to the death with the sinister Crawlers, it's startling just how aggressive she gets.