Doctor Death (Karl Helfern)

Year Zero
A member of a family of soldiers since at least World War II, Doctor Karl Helfern was a scientist working for Wayne Enterprises. Hired by Lucius Fox, along with fellow doctors Bill Kelver and Del Paji, he was known as the smartest among the group, working with nano-medicine to try and create a serum to make human bones harden upon impact to prevent breakage. The experiments were a failure and, presumably, led to his decreasing mental stability.

A variety of factors pushed Helfern over the edge. The first was the death of his son in the Middle East, which left him to believe that there was no sentimental force that could save people. The second was the loss of his job at Wayne Enterprises. Struggling to continue his research, he was approached by a pattern recognition expert, Edward Nygma, who agreed to fund the rest of the work, and inadvertently inspired the breakthrough which got the process working. Helfern, taking the name "Doctor Death", killed the other members of his research group by injecting them with his failed formula, causing their bones to grow uncontrollably and rip them apart from the inside.

Helfern faced the vigilante Batman on top of a weather balloon that the Riddler had placed above Gotham that, when the city power turned on, would give him full control of the city. The vigilante incapacitated Helfern by breaking his bones so they would regrow in an irregular fashion. However, Helfern would die when Nygma fired a missile to destroy the balloon.

Powers

 * Superhuman Strength
 * Regeneration: Because of the experiments, Dr. Helfern is able to recover from bone-breaking injuries, although with a disgusting wound.
 * Superhuman Stamina

Abilities

 * Chemistry: Helfern was a genius scientist who took his work too far and had no respect for life. His experiments, using himself as a specimen occasionally, only worked partially. Even years after his death, he was widely known for creating a regenerative formula for hard tissue, specifically bones.

Weaknesses

 * Monstrous Appearance