Aaron Helzinger (Prime Earth)

When the power went out in Gotham during the Zero Year Helzinger was in surgery at Gotham General Hospital, the doctors argued over whether or not to pull him out of the operation. Before they could decide, Helzinger woke in a monstrous rage, smashing through a window. The surgeons had been operating on his amygdala when they were interrupted.

After jumping out the window Amygdala encountered and attacked a young Dick Grayson, who was out with a group of new friends, away from the visiting Haly's Circus. With Helzinger chasing them, Dick decided to make a defensive stand in order to give his friends time to get away. Luring Helzinger onto a rooftop, Dick jumped to the next one over, and unable to make it across the gap, Helzinger fell, unable to get back up.^{[citation needed]}

Earning the nickname Amygdala, Aaron Helzinger spent much of his time incarcerated at Arkham Asylum, and later at Arkham Manor, when the asylum was destroyed.

When Arkham was rebuilt, he became partners with Solomon Grundy. Both of them attempted to fight Bane when Psycho Pirate was being kept in Arkham after they were all set free by Batman. They were subsequently beaten by Bane, before Bane was beaten by Batman. Later, they were fredd once again when Bane took over Gotham City. They then allied with Two-Face and in revolt against Bane, kiled Doctor Double X, one of Banes loyalists. They were then attacked by Gotham Girl and the new Batman, the former of which used heat vision to chop off Amygdala's arm.^[1]