Warhammer has Tzarina Katarin, the Ice Queen of Kislev, an extremely powerful sorceress capable of creating an entire new wing of her castle out of ice in a matter of hours and conjuring up blizzards so fierce as to stymie even the most bloodthirsty Orc WAAAGH!!!
Dungeons & Dragons has numerous variations and examples. Aside from the various deities of cold and winter, there's the Frostwind Virago that's the fey incarnation of the fickle and cruel nature of winter, the Frost Mage prestige class, the Winterhaunt of Iborighu prestige class, which eventually leads to transforming into an unholy abomination of ice and snow, the psionic Cryokineticist prestige class, and more.
D&D also has White Dragons, who have freezing breath instead of fire.
4th edition's different ruleset has killed "conjurer" and "evoker" wizard specialising, to be replaced by the classic elemental mages. Being an ice mage from level 1, with feats to match, is doable. 5th edition brought it back.
First edition had an evil humanoid race called "Frost Men'' who could shoot a "cone of cold" as an eye beam.
Jerza Wagner, a ghost from the Ravenloft setting, drains the living warmth from her victims and leaves them frozen solid. No, they don't wake up if you chip the ice away.
While the Darklord Meredoth is technically a necromancer, he uses lots of ice-based spells and has a frozen lair.
Champions, being a super-hero role-playing game, has clones of many popular superheroes and supervillains, including a Captain Ersatz of Iceman named Icestar. He lacks the former's frigid body-armor, but shares the wisecracking personality. (An old rules example for Presence Attacks has Icestar blasting a villain-carried crate and quipping, "Heads up, boys, the Good Humor man is here!")
Rifts has an optional Psychic Character Class called the Freezer, with various cryogenic powers.
Psychokinetic psions in White Wolf's Trinity could specialize in Cryokinesis, allowing them to freeze enemies.
The Winter Court from Changeling: The Lost get powers like this under the Contracts of Eternal Winter. They range from freezing any liquid solid instantly, to creating an aura of crippling cold, to causing a person to be hit by a hailstone the size of their head, to summoning a blizzard. Yes, even in hot climates.
Yu-Gi-Oh!: Even though Ghostrick Yuki-onna has the Dark Attribute, she has the effect of freezing her opponent if she gets destroyed.
Arduin RPG, The Compleat Arduin Book 2: Resources.
The Greater Demon Apharoe the Star Witch is immune to cold. The intense cold she radiates can cause weapons that hit her to break and if the weapon survives the being wielding it will suffer frostbite damage. She can fire beams of freezing energy from her fingertips that do 11-20 Hit Points of frost damage. She can turn any creature she touches to ice once every three melee rounds. In 1-10 melee rounds she can summon 100-300 Freeze Bees to do her bidding.
Ice Demons are immune to cold and their claws and wings cause 1-10 and 1-6 Hit Points of cold damage, respectively, when they hit. They have a Breath Weapon of intense cold in a 30 foot by 10 foot cone that inflicts 17-36 Hit Points of damage. They can reduce the air temperature in a 15 foot radius area around them by 20 °F per melee round, to a minimum of -180 °F. For each 20 °F below zero all other creatures in the area take 1-2 Hit Points of cold damage per melee round. While in this or a similar cold zone the demon has improved saves and its Strength and Hit Points are doubled. It can create ice in any shape desired, up to 1 foot by 6 inches by 2 inches per second.
The Greater Demon Boreas the Winter Demon. His claws inflict 17-36 Hit Points of intense cold damage on a hit and create snowfall in a 10 foot radius that causes 5-10 Hit Points of cold damage per melee round. He can also create a snow storm that lasts 5 minutes three times per day or for 10 minutes once per day. He like to cast ice magik spells and has all of the powers of a regular Ice Demon.
Pathfinder has several monsters, including frost giants, white dragons, trolls, and some fey, which are heavily associated with cold and ice, or use ice Breath Weapons or magic to attack, mostly found in the area around the far-north country of Irrisen, which is locked in an eternal winter and ruled by a witch who primarily uses ice magic. Player Characters can get in on this too with the abundance of magic spells that conjure ice or deal cold damage, especially so with things like the Winter Witch archetype (for the Witch class) and the Boreal or Rime-Blooded sorcerer bloodlines, both of which give the PC several ice-related powers, up to and including the ability to summon a blizzard for the latter.
Absolute Zero in Sentinels of the Multiverse, being basically an Expy of Mr. Freeze as a superhero. Following a chemical accident, thermodynamics gets weird around him, and he can't survive at room temperatures. He operates as a superhero to pay off the expensive cooling suit that allows him to not spend his entire life in a refrigerated cell bored out of his skull. In the Iron Legacy timeline, his Elemental Wrath version goes past simply venting coolant and gains the ability to actually create ice, represented by his base power changing from "dealing damage to himself" (which combos with his specialist equipment) to "dealing damage to other people".