Dr. Victor Fries, through tragic circumstances, became known as the villain Mr. Freeze. Paul Dini and Bruce Timm re-imagined the entire history and motivation of Mr. Freeze to produce a villain that could be taken as both a believable character and a deadly, serious threat.
The creative team invented the character of the terminally ill Nora Fries to flesh out the backstory of a fully-realized tragic villain. It was the first complete overhaul of a pre-existing character in the DC Animated Universe, and to this day it is arguably the most successful.
The DC Animated Universe backstory on Mr. Freeze became so popular that it was used as the backstory in the Joel Shumacher film "Batman & Robin" (with Arnold Schwarzenegger as Mr. Freeze), as well as the comics.
After the tragic accident that soaked Dr. Fries' entire body with the freezing solution and rendered him unable to survive outside of a sub-zero environment, Victor Fries created a vacuum tight suit which maintained his body temperature at 50 degrees below zero and tripled his strength. After building a laser-powered cold gun, "Mister Freeze" was born.
Mr. Freeze's original character design for the series was done by comic book artist Mike Mignola, recently of Hellboy fame. Interestingly, Freeze bears a marked resemblance to other Mignola characters, most notably Herman von Klempt, a mad Nazi scientist whose disembodied head is kept in a glass tank and is attached to a robotic body. There is also a similarity with Mignola's "The Amazing Screw-On Head".
Check out the Mike Mignola Hellboy Herman Von Klempt head by Mezco HERE