Mad Hatter in Alice's Adventures!

Tarrant Hightopp, also know as The Mad Hatter or simply The Hatter, is the deuteragonist of the 2010 film Alice in Wonderland and the main protagonist in its sequel Alice Through the Looking Glass. He is a hat maker that has been poisoned by mercury, hence his orange hair. He is part of the resistance to bring down the Red Queen's command of Underland and thus end her bloody rule. He is portrayed by Johnny Depp.

Personality

Tarrant's origins involve him with the Hightopp Clan, a family of hatters, which was supposedly destroyed by the Jabberwock, sent by the Red Queen during a visit by the White Queen to their village on the "Horevendush Day". The Hightopps did not indeed perish though, as it turns out they were actually captured and imprisoned by the Red Queen out of revenge. Though the White Queen was safely spirited away, the Vorpal Sword (as well as her crown) was lost in the confusion. Tarrant was thought to be the only member of his clan left- everybody and everything else was supposedly killed or burned to the ground. Tarrant only escaped the destruction because he led the White Queen's panicked horse away from the initial attack. He returns after to find the village burnt to the ground, a shocked look on his face he bends down to pick up his trademark hat. When we next see his face it is clear from the half smile that his sanity has shattered. A scene of Tarrant's past can be seen-the Jabberwock blowing fire down on the clan, when he and Alice are travelling and they pass through the remains of his home, causing him to briefly flash back to the destruction.

The destruction of his clan broke something in Tarrant's mind - causing him to become detached from reality and also develop a slight split personality. When he becomes upset his eyes change from green to a golden yellow and he begins speaking in a noticeable Scottish brogue. Tarrant can become violent in this state unless someone snaps him out of it. Mallymkun the Dormouse snaps him out of it the first time by shouting, "Hatter!!" when he is about to attack the Chesire cat who he blames for the attack on his clan. Alice later snaps him out of one of his episodes when he is imprisoned at the Red Queen's castle making hats. Tarrant himself is vaguely aware of his personality problem telling Alice that he has to get out of the Red Queen's castle saying its getting harder for him to think clearly there. 

Source: Alice in Wonderland Wiki:  https://aliceinwonderland.fandom.com/wiki/Alice_in_Wonderland_Wiki