Mr. Freeze was one of the Dynamic Duo's greatest enemies. Freeze is a deformed blue man, obsessed with freezing things with his freeze ray. Sometimes he has hair and sometimes he doesn't.
During a fight in his secret laboratory some years ago, Dr. Art Schivel was covered in an experimental chemical he had been working with. Batman tried to save him, but the damage had already been done. The freezing chemical had somehow bonded with his body, and he could no longer survive in any temperature higher than fifty degrees below zero. From then on, he referred to himself only as Mister Freeze. His condition requires him to wear a cooling suit whenever he leaves his icy lair. Freeze's warped mind blamed Batman for all that had happened to him, and immediately vowed revenge.
Ever since he escaped from prison, Freeze has been trying to destroy Batman. He also often tries to freeze other people, or sometimes all of Gotham City. Though whether this is because he wants others to suffer as he suffers, or if he is only looking for companionship, is unknown. The mental damage has also caused him to go through extreme changes in his temperament.
After a run-in with Batman caused his body to become unable to survive in any temperatures higher than fifty degrees below zero, Mr. Freeze has developed highly advanced equipment to help him survive and to get revenge on Batman. His first suit was a plain white suit that kept his body cold if he were to enter environments that were too hot for him to survive. Freeze also used a high-tech freeze rifle that was able to shoot beams of extreme cold and extreme heat.
When Mr. Freeze returned, he had developed a new suit with jet nozzles that kept his head cold, which enabled him to survive most environments. His freeze gun had been replaced with a new one that fired extremely cold air in gas form, which allowed him to completely freeze entire rooms.
Just as Batman and Robin do not go at crime-fighting alone, Mr. Freeze needs fellow partners in crime to assist him with his malicious schemes.
- Chill (portrayed by Kem Dibbs) - Mr. Freeze's henchman.
- Shivers (portrayed by Nicky Blair) - Mr. Freeze's henchman.
- Nippy (portrayed by Guy Way) - Mr. Freeze's henchman.
- Moe (portrayed by Roy Sickner) - Mr. Freeze's henchman.
- Frosty (portrayed by H.M. Wynant) - Mr. Freeze's henchman.
- Chillblaine - Mr. Freeze's henchman.
- Kolevator (portrayed by John Zaremba) - Mr. Freeze's henchman.
- Glacia Glaze (portrayed by Leslie Parrish) - A female ice skater who assisted Mr. Freeze in capturing Professor Isaacson. Her real name is Emma Strunk.
- Phony Batmen - Mr, Freeze's henchman.
- Phony Mr Freezes - Mr. Freeze's henchman.
- Green Ice (portrayed by Otto Preminger)
- Deep Freeze (portrayed by Otto Preminger)
- Ice Spy (portrayed by Eli Wallach)
- The Duo Defy (portrayed by Eli Wallach)
- Emperor Penguin (depicted as Otto Preminger)
- The name Mister Freeze was created specifically for the series. Freeze's comics counterpart was originally dressed in a bright green costume and was named Mr. Zero. The original "Silver Age" backstory had him as a criminal scientist, whose prototype "Ice Gun" backfired, spraying its cryogenic chemicals on him, and thus requiring him to remain at subzero temperatures to stay alive.
- The Filmation animated series, which had much of the same backstory as the 1966 series, included Mr. Freeze, but had a slightly different origin. In this version he was an extraterrestrial criminal native to a planet that had much lower temperatures than Earth, but unlike the blue frostbitten skin of the live-action series, this Mr. Freeze appeared to be a Caucasian man. The concept that Mr. Freeze would die if exposed to any temperature hotter than -50 °F was retained however.
- Later "Post-Crisis on Infinite Earths" versions of the character in comics, animation and even the film Batman and Robin, had the character's real name as Victor Fries, a former cryogenics expert who suffered an industrial accident while attempting to cure his terminally ill wife Nora Fries.
- He is one of the only villains in the series to murder a character. Freezing Princess Sandra's butler and knocking him down following by a crashing noise, presumably breaking him to pieces.