Jervis Tetch was a psychotic and obsessive-compulsive disorder scientist who became the Mad Hatter and one of Batman's enemies following his unknown past.
He is one of Talia al Ghul's henchmen. Tetch has once used his abilities to shape the previously empty mind of Heretic (a clone of Damian Wayne) into a perfect soldier for his master's organization the League of Assassins. After Batman is captured by the Heretic and taken into their headquarters, the Mad Hatter reprograms his brain into devotedly following Talia al Ghul's orders and revealing all of his and his allies' secrets. With Batman's help, the League of Assassins infiltrates the World Tech Summit in Gotham hosted by Bruce Wayne and takes over Wayne Enterprises' technologies. Tetch starts to brainwash all the attending politicians and dignitaries into obeying Talia. However, he is killed by a system overload caused in the ensuing battle between Batman's allies and Talia's henchmen halting the process. The overload causes his head to explode.
- Similar to all henchmen of Talia in Batman: Bad Blood, he learns Batman's secret identity but is killed, ensuring his identity remains secret.
- This Mad Hatter's desgin would be later used in Young Justice: Outsiders.
- His villain name Mad Hatter is based on the same character from Alice in Wonderland.