Dead Space: Martyr/YMMV

• Complete Monster: Markoff, Stevens and Krax. They all do some pretty cruel things throughout the course of the novel, but Markoff and Stevens definitely reach the Moral Event Horizon in the novel's epilogue when they force Michael Altman to fight off their new Necromorph type (which happens to have been partially created from Krax after Markoff decided he was "expendable") with a spoon, while they watch from above drinking champagne and grinning to each other.
• Moral Event Horizon: Markoff and Stevens killing Michael Altman.
• The Woobie: Michael Altman