Doctor Death (Dr. Karl Hellfern) is a supervillain appearing in publications by DC Comics, primarily as an enemy of Batman.

[4] In his first appearance in Detective Comics #29, Doctor Death develops a lethal chemical agent from pollen extract and plans to use the poison to extort money from wealthy Gotham City citizens.

With a new accomplice, a Cossack named Mikhail, Doctor Death is this time successful in claiming a victim in his extortion scheme, but discovers from the widow that the poisoned man lost his fortune in the Great Depression.

[8] After several decades' absence, writer Gerry Conway reintroduced Doctor Death in Batman #345 and Detective Comics #512 (1982).

[10][11][12] In The New 52 continuity reboot, Doctor Death is a disgruntled former Wayne Enterprises scientist who created a serum that causes uncontrolled bone growth and possesses a skeletal appearance due to testing it on himself.