Batman & Mr. Freeze: SubZero

Batman & Mr. Freeze: SubZero is the second movie spun off from Batman the Animated Series. If you were looking for the time Batman actually met Sub-Zero, that didn't happen for a few more years (and Mister Freeze wasn't involved).

Victor Fries alias Mister Freeze has made a home for himself in the Arctic, where he has the peace to continue working on a cure for his cryonically preserved wife, Nora, in the company of Inuit boy Kunac and two fully grown polar bears. As you might expect, this doesn't last long — a luckless submarine crew has the misfortune to surface right in the middle of his home, shattering Nora's preservation chamber. Enraged, Victor turns his freeze gun on them all before returning to Gotham in search of help.

The good news: He finds an old colleague, Dr Gregory Belson, who is heavily in debt and desperately in need of a windfall — which Victor can provide, having discovered a large vein of gold in the Arctic. The bad news: The only thing that can save Nora is an organ transplant, there aren't any deceased donors with her rare blood type, and any living one would die. Victor is undeterred, and the two of them quickly pick a target: Barbara Gordon.

While it lacks the near-cult status and awesome soundtrack of Batman: Mask of the Phantasm this movie was a critical and commercial success and is currently the third-highest rated Batman film on RottenTomatoes.com, with 90% to The Dark Knight's 94% and Batman: Under the Red Hood 100%.

Tropes used in Batman & Mr. Freeze: SubZero include:

Action Girl: Barbara, obviously.
Air Vent Passageway: Barbara gets out of her cell this way, only to discover that they're on an abandoned oil rig.
Almost Kiss: Dick and Barbara at Shaugnessy's, but they're interrupted by a supervillain and his pet polar bears. Just another night in Gotham.
Animation Bump
Art Evolution: The film was made using the more detailed style of the original BTAS designs but was made during TNBA era, which was appreciated by fans.
Barbara Gordon Held Hostage: Out of the 18 possible donors in Gotham, Belson picked the superheroine. She also happens to be the Police Commissioner's daughter, which Belson should have known.
Anti-Villain: Mr. Freeze, again.
Billy Needs an Organ: They make it through the entire movie without ever specifying which one(s), only that the donor cannot survive after removal.
Conspicuous CGI: And it really doesn't mesh with the art style.
Contrived Coincidence: That they picked the police commissioner's daughter, instead of the 17 other people on that list.
Cool Plane
Description Cut: Three in a row when Commissioner Gordon's talking about Barbara at the beginning.
Dirty Coward: Belson leaves Freeze to die out of fear for his own safety. The heroes then risk their lives to save him while Belson gets fatally smacked with karma.
Damsel in Distress: Barbara, though she only agrees to go with Victor after he starts threatening bystanders and repeatedly attempts to escape.
- In other words, a Badass Damsel.
Even Evil Has Standards: Subverted. When Freeze makes it clear to Belson that he's planning to kill Barbara to save Nora, the scene begins to play out like a typical Even Evil Has Standards moment....and then it's shown that Belson actually is acting disgusted and reluctant about doing it because he feels Mr. Freeze isn't paying him enough for it. He happily goes along with it once Freeze ups the payment.
Everything's Worse with Bears
Falling Chandelier of Doom
Family-Unfriendly Death: See above. Belson dies screaming as the burning oil rig collapses on him.
Getting Crap Past the Radar: The scene that starts with Barbara groaning offscreen while her bed moving about heavily feels like this.
Heartwarming Orphan: Kunac
Hero Stole My Bike: Dick Grayson takes a random guy's motorcycle while pursuing Freeze, but gives him the keys to his Corvette in exchange.
If I Do Not Return

Batman: If I'm not back in time go without me!
Robin: WHAT!?

Jerkass: Belson is willing to go along with Victor's plan just so he can get himself out of debt, regardless of whatever happens to Barbara. See the Even Evil Has Standards subversion.
Karma Houdini: Mr. Freeze. He kills a submarine crew for accidently wrecking his Artic hideout, and was the one who instigated the plan to kidnap Barbara to harvest her organs, yet he is Easily Forgiven for the finale because he breaks his leg and Norah is put in danger. It wouldn't have been so bad if he'd actually died in the end, but he survives and it leaves mixed feelings.
Lighter and Softer: While this film is still not a lighter hearted kids' cartoon, it is not nearly as dark as the previous film, Batman: Mask of the Phantasm.
Love Makes You Evil
Magic Skirt
Missing Trailer Scene: In a unique application of this trope, the commercials for this movie consisted entirely of scene from Mr. Freeze's previous appearances on Batman the Animated Series.
The Other Darrin: Melissa Gilbert was replaced by Mary Kay Bergman as the voice of Barbara Gordon. Tara Strong would replace her when B:TAS became The New Batman Adventures.
Parental Abandonment: Kunac.
Right-Hand Attack Dog: Notchka and Shaka, Mr Freeze's two loyal polar bears.
Say My Name
Save the Villain: All three heroes help Freeze after he gets pinned by debris. He then helps them rescue Nora and Kunac, and Batman tries to save him even when the oil rig is about to go up in flames.
Sexy Backless Outfit: Barbara at the fundraiser.
Shipper on Deck: Commissioner Gordon is very obviously a Dick/Barbara shipper.
Shrug of God: Is this film set before or after Batman and Robin find out Barbara is Batgirl? It was constructed so as not to contradict either possible answer.
Stealth Hi Bye: Batman and Robin. They do this the way the rest of us breathe.
Tranquil Fury: Robin is noticeably quieter than his usual DCAU appearances, but after Barbara is kidnapped he's really, really pissed off.
You're Insane!