As Seen In: Martyrs (2008)
Without spoiling the underlying theme in French filmmaker Pascal Laugier's divisive 2008 horror film Martyrs, let's explain what happens to the resilient Anna (Morjana Alaoui) on a surface level. She's captured by a malicious group of people, trapped in the basement of an otherwise normal-looking home, routinely beaten, starved, and subjected to a variety of systematic torture methods.
Eventually she's unable to do little more than breathe. Anna is then brought into a surgeon's workplace, completely skinned, and hoisted into a crucifixion-like position and left to naturally die. By which time death is indeed merciful.