Death's Head is ?.
Paxton Page was a scientist who created the cobalt bomb. Because he refused to sell his creation to anyone, even the US government, he was branded a traitor. He continued his research as a recluse and was driven mad by the cobalt radiation, which also gave him super-powers. He took on the identity of Death's Head and drove off any unwelcome visitors to his estate.
When his daughter Karen returned home, to try and get away from her grief over Matt Murdock's death, Daredevil followed her, in order to explain how he had killed off his alternate identity of Matt Murdock. Death's Head and Daredevil fought in Paxton's laboratory, during which a vat of molten cobalt was about to spill over Karen. Paxton pushed her to safety and was killed by the liquid.