Characteristics:

Victor Fries was a talented scientist, with a horrible past (a violent father, no friends) that married the love of his life, Nora Fries.

When Nora is diagnosed with a rare terminal illness, Victor's life begins to spiral downhill. In a desperate attempt to save her life, he begins work at a large corporate company run by the evil and corrupted Ferris Boyle.

Fries, as he cannot find a way to cure Nora, finds a way to place her in cryo-statis. In order to do save Nora he has to steal equipment from the company he is working for.

When Ferris finds out about Fries stealing from him, he and some of his goons try to kill Fries in the cryo lab. This results in an accident changing Fries so that he can only live in subzero temperatures.

To counter this, Fries builds himself a cryo-suit to keep his body temperature below zero (powered by diamonds) and an ice gun. Mr. Freeze is born.

Nearly all of Mr. Freeze's crimes are attempts to try and save Nora's life, although he has also tried to take revenge for his mutation on Ferris. Mr. Freeze finally killed Ferris. Mr. Freeze´s weak point, then, was his helmet, that was broken by Batman, seriously damaging his cryo-suit, and allowing the Dark Knight to catch Fries, who later, fixed it.

The main difference between Freeze and the other Batman´s foes is that he isn´t a madman like Joker. Freeze´s actions use to have logic and a deep motivation (to collect diamonds to preserve his life and find a way to save his wife). This explains that he doesn´t use to collaborate with the other Gotham´s criminals. An exception happenned during "Dark victory", when he worked with Two Faces. Two Faces payed him a lot of money, and Freeze helped him to escape jail and to kill some mob´s bosses. It must be noted that Harvey Dent had Freeze´s simpathy because of his strange and tragic situation with his wife, Gilda Dent.
Also, sometimes when he´s very enraged, frustrated or confused, Freeze has arrived to attack directly Gotham´s inhabitants ("Batman: Mr. Freeze"), killing innocents, but it isn´t his habitual behavior. He isn´t a mass-murderer, like Poison Ivy or Joker. 

During "No man´s land", he took control of Gotham during some weeks. His kingdom was defined as the less brutal, compared with Killer Croc´s occupation.

Mr. Freeze has defeated during his career Robin (Tim Drake) and Batgirl (the last one). He also survied to the attack of a Predator ("Batman VS Predator III"). Also, his frozing technology defeated Catwoman (in Rome) and a Predator (when Batman used Freeze´s weapon).

Freeze showed also his good deeds years ago, helping Flash to solve a crime. He also helped Batman to defeat Clayface ("Shadow of the Bat 75", but only because Batman manipulated him), and also, recently, helped Batgirl to defeat Ra´s Al Ghul´s plans of world destruction.

In 2005 ("Legends of the Dark Knight 190-1"), he suffered a depression, caused by his lack of success healing / ressurecting his wife, and considered the idea of suicide, but Batman saved him. In that episode, he defeated Batman with gas, but forgived his life. He also, months later, ("Gotham Knights, 59") captured Batman again, and created a trap that would have killed Batman and himself, but Freeze had a long conversation with Batman, and finally recovered his aim, and even helped Batman to escape. Since then, his depression finished, and Freeze recovered his strength to save his wife.

During Salvation Run he was one of the few Batman´s foes that joined Luthor´s side, instead of Joker´s. In that comic, he destroyed some of Darkseid´s demons, frozing them (obviously).

Recently, he also ressurected his wife using a Lazarus´ pit.

In Batman´s TV series, starred by Adam West, he was played by George Sanders (first) and Eli Wallach (later). In the movie Batman and Robin he is played by Arnold Schwarzenegger. In Batman and Robin, Mr. Freeze and Poison Ivy are the two villains, but in the last scenes, Freeze is redeemed by Batman, and saves Alfred Pennyworth´s life. 
He has a big part in Batman: The Animated Series and he was also in the New Batman Adventures and Batman Beyond.

Batman: The Animated Series

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Mr. Freeze as he appeared in B:TAS.

When Mr. Freeze first appeared in Batman: The Animated Series (part of the DC Animated Universe), he had gone through a monumental change from his original comic counter-part. Bruce Timm had transformed him into a victim of injustice and a hero in his own mind. This version was well accepted by fans and became canon in the regular DC Universe, after Paul Dini´s one-shot comic book "Batman: Mr. Freeze".
Freeze would go own to make numerous appearances in the DC Animated Universe, even in the future of "Batman Beyond".