Captain Marvel Jr #12 (1943)

Freddy personally delivers a paper to the door of one of his regulars, Professor Quiddle, who hasn't been by in some time. He's greeted and turned away at the door by Eza Zombey, Quiddle's skull-faced manservant. Suspicious, Freddy transforms and flies through an open window to investigate. Quiddle's there, and quite annoyed to have his latest project interrupted. He orders Zombey to eject Captain Marvel Jr., who promptly tosses Zombey aside. To the young hero's surprise, Zombey just gets right back up attack again every time he gets knocked down. Quiddle explains his servant's a zombie imported from Haiti, and has supernatural vigor. Furthermore, because zombies aren't illegal, Jr. has no say and is forced to leave. Soon, Freddy sees Eza Zombey again, attending a party in Quiddle's place because the scientist finds those social engagements so tiring. Zombey soon makes eyes at a young socialite and is challenged to a duel by one of her other suitors. They do pistols at ten paces, and while Zombey's unharmed because he's one of the living dead, his opponent only survives because Zombey's gun was actually unloaded the whole time. Freddy tries again to convince Quiddle to get rid of the zombie, as a man almost died because of him. Quiddle adamantly refuses, as he explains he's trying to learn the secret behind the zombie's immunity to pain, which he plains to bequeath the world. Freddy knows enough to understand it's only because Zombey's the walking dead, and anything Quiddle learned from him would be nothing but harmful to living humans. He manages to transform and forces Quiddle to remove Zombey from normal society, but the scientist protests that he can't: the zombie's enchanted to be his slave. After completing any task he's given, he comes right back. Jr. has an answer to that: have the zombie enlist in the army and put his invulnerability to use against the Axis.