Mr. Freeze is seen by many as one of Batman’s most sympathetic villains, and this is thanks to Batman: The Animated Series. Mr. Freeze was initially a fairly one-note character that the Batman comics themselves became dismissive of, with the cold-themed mad scientist retaining relevance thanks to the 60s Batman TV show. The animated series, however, rewrote Mr. Freeze, imbuing him with depth and tragedy that became permanent fixtures of the character.
Mr. Freeze was originally called “Mr. Zero,” debuting in a 1959 issue of Batman. Due to a laboratory accident, Mr. Zero cannot survive outside of sub-zero temperatures, forcing him to wear his signature suit. Armed with an energy weapon that freezes materials, Mr. Zero made several appearances in the Batman television series, which renamed him Mr. Freeze, a moniker that he’d use in all future iterations.
Mr. Freeze was killed by the Joker in the first issue of 1991’s Robin II, seemingly putting an end to the villain. Less than a year later, Batman: The Animated Series revamped Mr. Freeze, giving him a new origin as a scientist desperate to save his terminally ill wife, leading to both his lab accident and subsequent life of crime. Mr. Freeze returned from his apparent demise in a 1994 issue of Detective Comics, and his new origin from the animated series was retroactively added to the comics and used in most subsequent iterations of the villain. Giving Mr. Freeze such a sympathetic motivation imbued the character with an extra layer of pathos, making him one of the most relatable characters in Batman's entire rogues' gallery.
Mr. Freeze’s cinematic debut in Batman & Robin adapted elements of his animated series origin, allowing the film to give him a redemption of sorts when Batman vows to help him discover a cure for his wife’s condition. This was also the case in the critically-acclaimed Batman Arkham video games, which features a tragic yet definitive ending for Mr. Freeze in Arkham Knight. While previously little more than a mad scientist with a cold gimmick, Mr. Freeze became a morally complex and sympathetic character whose turn to villainy was the tragic result of desperation to save a loved one.
Batman has one of the most iconic rogues' galleries in the superhero genre, but most of his villains aren’t depicted as redeemably as Mr. Freeze. Characters like The Joker, Riddler, or Two-Face may have origins with tragic elements, but they’re typically shown to be too far gone to end their criminal activities. Mr. Freeze committed crimes to save his wife, not outwit Batman or settle a score with society, so his new origin gave him a fundamental potential for redemption.
Not all recent iterations of Mr. Freeze used his tragic animated series origin, however. In 2004’s The Batman TV series, Mr. Freeze was an ordinary criminal with no scientific background who gained cryokinetic powers in a lab accident while fleeing Batman. The New 52 comic relaunch utilized elements of Mr. Freeze’s animated series origin, though his “wife” was actually a cryogenically frozen test subject who didn’t meet Mr. Freeze until she was thawed. Mr. Freeze’s best-known origin in the Batman mythos, however, comes from Batman: The Animated Series, which made him a tragic and sympathetic supervillain.