The Mad Hatter as portrayed in Batman: The Animated Series. Voiced by Roddy McDowell.
History
Jervis Tetch was a meak scientist experimenting with mind control equipment, who had a romantic intrest in his his co-worker Alice. He was frustrated upon hearing that she had a boyfriend. But when news reached him that their relationship had sunk he made it his top priority to impress her (With a little help fron his mind control chips). He dressed up as the Mad Hatter character from his favourite story book and set of with a bunch of flowers ready to make his move. Alice was charmed by Jervis but misinterprated his gesture as one to cheer her up. Alice mended her relationship and got back together with her love lost (much to Tetch's dissapproval). His attempts at impressing Alice involved him brainwashing people to pretend that his was a "man about town" or "a celebrity". This brought him to the attention of Batman. When Batman confronted two hooligans that Jervis had mind controlled and told to "jump of a bridge or something!". Batman stopped the two from committing suicide and noticed that in there hats where 10/6 labels. These "labels" where mind control chips and the Dark Knight suddenly remembered seeing a picture of the Mad Hatter in which his hat label was like this. He saw it in the office of Jervis Tetch. Jervis now calling himself the Mad Hatter has brainwashed Alice and kidnapped her. He'll have her mind or no mind! Batman is soon on his trail where he encounters the Mad Hatter at an amusement park with an Alice in Wonderland section, he has brainwashed people to dress up as Wonderland characters and kill Batman. Batman releases them from the maniacs spell and confronts the Mad Hatter. The Hatter armed with an axe fights him but a huge ornament of the Jabberwock falls down upon him (when Batman throws a batarang at the string of the model). Alice is freeded from the Hatters spell and rejoins her sweetheart. The Hatter trapped under the Jabberwock model quotes Alice in Wonderland with all the sadness of the Mock Turtle. (BTA: Mad as a Hatter)
Bruce Wayne finds himself trapped in a dreamworld where his parents are alive. He's engaged to Selina Kyle and isn't Batman. He is maddened to find that all the words in every book and newspaper are backwards. Bruce finds that this world does have a Batman. Who seems more brillant than he ever was. He confronts this otherworld Batman and pulls off his cowell to reveal Jervis Tetch. He takes to the Hatter and comes to the conclusion that all this happiness is a dream. And he needs to wakeup so he throws himself off a building. He wakes up as Batman. The Mad Hatter captured him and projected these images into his head so that he could have his very own "Wonderland". When Batman finally freed himself from the equipment the Hatter was using, he demanded to know why Tetch had used the machine rather than simply kill him. Sobbing, Tetch replies, "You ruined my life! I was willing to give you any life you wanted, just to keep you out of mine!". Jervis was arrested and returned to Arkham Asylum where he probably escaped from. (BTA: Perchance to dream)
The Mad Hatter was one of the many Arkham Villains who escaped and put Batman on trial under the claims that "He created them". He was the main member of the jury and was the one who announced the verdict. He was also called to the stand and asked did he really need to stalk Alice? His reply shocked the jury as he said he would rather of let her die! (BTA: The Trail)
He used his mind control equipment to his advantage and brainwashed many people to do his bidding (BTA: The Worry Men)
The Joker stole his mind control devices for his own use. He brainwashed famous people to become villains and also brainwashed Tetch himself to fall into a sort of deep open-eyed sleep. (BTA: Make Em laugh)
He is also seen in Arkham playing chess with the Scarecrow. He also appeared telling the Joker to turn back to the previous T.V channel or in this case "Hey! I was watching that!" (BTA: Jokers Wild)
Redesign
The Mad Hatter as he was later depicted in The New Batman Adventures
When the series was later redesigned. The Mad Hatter character design was radically changed. Looking more short and rat like, the Hatter was an albino, white haired man in green clothes. This change was made in effort to make the character more like the orginal Hatter from Alice in Wonderland. Many fans where not pleased by the change.
He appeared on T.V