Doing it Wrighte: Mr. Freeze

Originally Mr. Freeze was an unimportant batman villain from the age of camp who had an every day run of the mill, "kicking sand in physics face" style freeze gun, and a metabolism that was only fine at temperatures bellow zero degrees of one sort of another.  This all changed significantly when the writers for the Batman The Animated Series had the audacity to give him a good back story and character motivation as well as a new, colder, personality to go with it.  To give the executive summary:

This version of Freeze started out as a really strong tragic villain, but his main motivation was resolved in his introductory episode.  This lead to his wife un-dying for the movie "Batman & Mr. Freeze: SubZero", which wrapped up what few loose end motivations Victor had for doing bad things, and is probably why the cryo-disease becomes the central drive behind all future episodes with this character, as there was little else to do that wouldn't heavily diminish the character's portrayal.  The strongest thing about this interpretation of Freeze is how far removed he is from a normal Batman villain.  He doesn't rob banks, extort money or plan any complex terrorist acts possibly involving balloons, but instead is motivated by by revenge, jealousy, and self preservation.  The two weakest things about this version of Freeze is his costume design (fish bowl head and very inflexible looking heavy armored suit seems a bit contradictory), and his freeze gun, which spontaneously creates ice via what I like to call "Super Science!", which works better in a science fiction setting than a vaguely modernish Gothic superhero setting like Batman the Animated Series had, though there's little flexibility in what you can have a cryogenic scientist do weapon wise that makes him stand out.

Another example of this line of Freeze design is the should-be-expunged-from-the-bowels-of-history "movie" Batman and Robin:

In spite of the fact that this film is cinema's greatest violation of the Geneva convention, I actually genuinely liked Arnold Schwarzenegger's performance, and the portrayal of the new, vastly improved, ideas for Mr. Freeze in an old fashioned, campy, way.  Also, the naturally shorter length of the movie lets the focus lie completely behind the main motivations of Mr. Freeze, and eliminates the need to keep coming up with reasons to give him more episodes, thus letting the focus stay on the tragic tale of his frozen ill wife and the accident that turned him into a walking revenge machine.  Unfortunately, this film is Batman and Robin, so all these interesting concepts get eaten up by a lack of screen time and focus due to the rest of the film's plot*.

While both of these Freezes may have missed the perfect mark here or there, they were wildly better than one that came after them:

While Mr. Vanilla-Sundae-of-a-villain-origin here completely throws out the tragic background element that made his DCAU counterpart an interesting and compelling figure in favor of the old "Skin Bleached = Life of Crime" logic, this character has two things going for him: the costume and he's a cryokinetic.  His costume replaces the red goggle fish tank head in favor of ice created by his own powers, thus taking away the impractical glass part for something both more thematic and significantly more awesome looking, though it still has what looks like some kind of refrigeration unit, which you think his power would make pointless.  As for giving Freeze cryokinesis, this was actually a good idea as it gets away from the gun, that does basically the same thing but hurts your head to think about, for an easy to justify ability that needs little explanation and makes the man dangerous in his own right (random powers easily falling in the category of suspension of disbelief in a superhero themed world), as opposed to an immortal with special temperature needs waiting to be offed by a hair dryer.

Since this article was first made there has been a new Freeze presented to us via the New 52:

While this Freeze parallels the DCAU concept, it takes a much darker and more psychotic turn which, if you are someone that finds "Heart of Ice" to be sacrosanct, seems borderline blasphemous, but this Freeze has an advantage that the more tragic and sympathetic DCAU one lacks; reuse-ability.  A classic character in a modern comic book like Batman and related such titles(which accounts for ~25% of DC's comics line currently) needs to be able to make several appearances in justifiable ways, and the more easily resolved and sympathetic DCAU Freeze simply does not fill that role as well as this mentally ill cryophile(blasphemous scholars will lie and tell you this isn't actually a word.).  Furthermore, this Freeze fits a lot better into Batman's modern rogue's gallery and actually belongs in Arkham Asylum along with the rest of his mentally ill murderous bastards who are always being held with the tightest security so that they will never escape on a Tuesday(other days of the week the security consists of the B team due to budgeting issues).

Looking at all of the icy ground already covered by past Freeze design, if I was designing a new take on the Frosty villain, (presumably because DC comics and WB decided to make a reality TV show with the a slightly less stupid premise than most and my name got picked from the Facebook at random) I would take some of the best ideas from the above and add them to a blender, then hand them off to a crack writing team, or a random desperate college intern, and then go for a cup of coffee and a scone.  Said ideas would be:

Victor Fries is an ice cream sales man who gets bitten by an experimental radioactive vanilla snow cone and.... no, wait, that's a terrible idea.  Who the hell would think radiation could give you super powers.

Victor Fries is an ice cream sales man who gets bitten by an experimental genetically modified vanilla snow cone and gains the proportionate powers of a.... no, wait, different genetic material introduced into someones body would be fought off by the their immune system which would either purge you of said material or kill you in the process.

Victor Fries is not an ice cream sales man, but instead is some normal guy (actually he could be an ice cream salesman but that's not the point) who, while trying to find treatment for his terminally ill wife, ends up in some completely unlikely "Super Science!" facility and somehow has a terrible power giving accident involving a genetically modified radioactive vanilla snow cone experimental cryo-chemicals of an unknown and purposefully vague nature that gives him cryokinetics, an obvious pale skin tone and extreme tolerance for the cold.  He then steals the blue prints for a freeze gun a cryo-capsule which he gets the parts to build via theft and puts his wife in, all the while being hunted by said company who is a bit pissed off at the stain he left in the lobby, to say nothing about the stolen blue prints and disaster with the chemicals.  After the introductory story resolves, Fries' wife is in cryo-stasis somewhere only Fries knows of and Fries is a fugitive using the money from his robberies to research vanilla snow cones a cure for his wife using the underworld to launder the money in order for a front business to do the necessary investing into the research, which in turn means Fries has to do some heavy lifting for some unsavory people until the whole situation turns sour and Fries gives them the cold shoulder.  Fries also wears a costume that looks similar to the one from The Batman to keep everyone not named Batman from figuring out his true identity and motives.  Victor Fries is actually an alias; his real name is Peter Parker Victor Freeman or something like that.

With a background something like the above you can easily stretch out and make a decent variety of stories involving Freeze, paint a detailed character through his interactions with the heroes and villains alike as well as some inner monologue, and set him up for the great metaphorical balls kicking.  He is a tragic villain after all, so in the end his means will have to catch up to him and either he'll break and become a true sociopath, or Gotham cities unique volunteer public servants will help him straighten his life out with some good old fashioned violence.

Obviously there's other things that are equally as good or better that you can do with a character like Mr. Freeze, but he is a great study of the tragic villain and a genuinely interesting character in everything modern not titled The Batman.