Mad Hatter (Arkhamverse)

Batman: Arkham Asylum
The Mad Hatter is refrenced in Batman: Arkham Asylum, in which his bio can be unlocked by scanning a tea set in the Botanical gardens, which is also the answer to the riddle: "What time is Tea time in Wonderland?" Also, his name appears on the party list. Jervis Tetch's page in Dr. Young's book shows a Riddler's question mark, which means a relationship in defeating Batman by using mind control or word games, and to make this evidence true, Mad Hatter was treated by Hush which Riddler knows about his schedule so he could sneak out and see him about a plan. Also, the Tweeds and him share a common interest in Alice in Wonderland.

Batman: Arkham City
Mad Hatter appears only in a side mission which is unlocked after a cutscene where the Mad Hatter makes a brief cameo. Hatter kidnaps Batman when he falls into Hatter's trap which he baited with a hallucination of what Batman most desired, which was the cure to the virus Batman contracted from the Joker. He then attempts to control Batman with a special mask he created for him, but Batman breaks through with sheer will and eventually defeats him.

Psychological Profile (by Dr. Young)
The Mad Hatter

Real Name: Jervis Tetch

DOSAGE SHOULD BE HEAVILY INCREASED.

Psychological Profile: Tetch is a classic delusional who also displays an obsessive ideation based on hats. He believes that he is the true-life incarnation of the Mad Hatter from Alice's Adventures in Wonderland. Tetch's skills as a hypnotist and his frankly inexplicable talent for inventions involving mind control make him at times a dangerous patient to treat, or they would for a less stable and insightful doctor than myself.

Additional Notes:

Tetch is completely unmanageable when forced to bare his head, so the regulation of Arkham patient uniform rules have been relaxed in this area to facilitate his treatment.