Heath Mansel

Heath Munsell, was originally the leader of the current Survey Corps. Seeing that he was commander he was probably mildly intelligent and brave. He was killed in an expedition, and later a titan tossed his decapitated head over the wall. Which was unfortunate as his wife, Elena Munsell, saw his head.

Elena later joined a group of titan worshippers and proceeded to open the gates, allowing a titan to get in. The manga later confirmed that five thousand people or so, were killed in this break in.