The DCU is chock full of these guys, including (but definitely not limited to):
Dr. Victor Fries/Mr. Freeze from Batman. Unlike other examples, though, his ice-based abilities are not actually powers per se, but ice-based weapons. However, thanks to an unfortunate accident, he can't survive temperatures above freezing, making him a literal ice person.
The Flash villain Captain Cold, whose "cold gun" reaches temperatures of absolute zero, which causes water molecules in the air to immediately form ice, which can be used to freeze people (though because of his code against killing innocents, he usually simply holds people in suspended animation rather than outright kill them), create objects from ice, and also to produce a "cold field" which slows down things around him and is used as explanation as to why he might be able to deal with the Flash.
In the New 52, he seems to no longer require the cold gun until Forever Evil, where he needs to use it again.
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The pre-New 52 Killer Frosts are an interesting variant as well: apparently created by someone with slightly more understanding of thermodynamics than most Ice People, they absorb heat, rather than projecting cold. This means you can't Kill Them With Fire.
Made extra interesting by the fact that attempting to Kill Them With Fire just makes them happy — they use the powers because they can't get warm, due to a side-effect of getting them. Ironically this also means that freezing them is even more effective against them than it would be on normal people.
The New 52 Killer Frost puts a different spin on it, absorbing others' body heat to keep herself warm. Supers with fire/energy powers, though, can have unpredictable effects on her. No word on what natural or man-made fires would do.
Tora Olafsdotter/Ice. She can, at will, project in various forms quantities of ice and snow through her hands just enough to down an opponent. She can create platforms of ice upon which she can skate. In the Red Daughter of KryptonSupergirl storyline she used her ice powers to freeze a super-villain who was kicking the butts of three Red Lanterns.
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Sigrid Nansen/Icemaiden, who briefly replaced Ice in the Justice League. Her greatest ability is to become very cold and create ice armor in times of great stress.
Dr. Joar Mahkent and his son, Cameron (both codenamed Icicle), two Justice Society of America villains. The first was a normal human with a Freeze Ray. His son Cameron, the second Icicle, can generate and control ice. This is because his father's prolonged exposure to the weapon altered his genetics, allowing him to biologically pass down to his son the ability to freeze objects and people or to lower the temperature of a room or other area.
An issue of Justice League Adventures featured a team-up of Icicle, Mr. Freeze, Captain Cold, Killer Frost, obscure Wonder Woman foe Minister Blizzard, even more obscure Outsiders foe the Cryonic Man, and downright "Sorry, who?" Batman foe the Snowman. All led by Polar Lord, a new villain from Polar Boy's home planet. The story was called "Cold War".
And the team of villains was called the "Ice Pack".
Elijah Snow from Planetary. Not quite frost projection, but the ability to draw heat out of an object on a molecular level; in his second appearance, he turns nerve gas to slush.
Superman, Supergirl and other Kryptonians can expel huge amounts of super-cold air to freeze their opponents with or put out fires. Bizarrogirl has freezing eye-beams.
Aquaman also fits into this trope since his acquisition of an Ancient Artifact which, if myth can be believed, not only holds power over the seven seas of the entire world but all the elements connected with said ocean lord.
The N52 version can similarly claim this with his new Prongs of Poseidon allotted him by the aforementioned sea god to utilize with lethal effect
Garth, the original Aqualad, can control the temperature of water which allows him to heat it up or freeze it.
Coldsnap, a member of the Outsiders villain team The Masters of Disaster, has this power. He's paired, thematically and romantically, with Heatstroke, but because of their powers they can never make physical contact.
Bobby Drake, aka Iceman, from X-Men. That's just how he started out — turns out, he's an Omega-level mutant (that means his full potential is Phoenix-class!) with complete control over moisture. When Emma Frost (who is a psychic and normally has nothing to do with ice despite the name and the white outfit) took his body over, she did things with his powers that he could never do on his own... but he's learning bit by bit.
In the Draco story arc, Bobby Drake gets his head cut off (in Ice form). He later reforms it using the water coming from a demon opponent. Later, Beast issues a research paper regarding this unique mutation for Iceman.
He once cured himself of poisoning by replacing his entire body with new ice little by little this way.
Storm also has some Ice powers in the form of creating blizzards, but this is usually de-emphaized due to Superhero Speciation, and she uses more of her Thunderstorm and Tornado abilities. In the animated series, where Iceman wasn't around, Storm was more than happy to whip up blizzards that could flash-freeze things fairly quickly (though not as quickly as Iceman).
The minor villain from Iron Man, Blizzard, in his multiple incarnations. All the Blizzards have similar powers, derived from their costumes. Micro-circuited cryogenic units make it possible to emit freezing rays, which lower the temperature of the surrounding air (or objects) and release ice as a projectile.
Skurge the Executioner. Using his Axe, he opens a portal (by cutting the air) to a dimension of cold, letting the icy wind blow onto his enemies. He can also do the same thing with a dimension of fire.
Ymir can create blizzards with no effort, among other such Ice-related abilities (he is much stronger than most Giants, as he is the original Norse one). However, unlike Frost Giants, he is an Ice Giant and seems to be literal living ice.
Kelda has weather control powers, which includes generating ice and forming weapons from it. And she can make poisonous ice.
Loki has many mystical powers at his disposal, but he's got a talent for ice magic thanks to his Frost Giant heritage.
In Runaways (2015), Sanna Strand is capable of generating ice from her hands.
Sub-Zero, from Blue Bolt Comics, gained ice powers when his spaceship passed through a comet.
Tor from Crack Comics had control over ice.
Frostbite from DV 8 has an odd twist on the formula: his power is absorbing heat. He uses this to freeze enemies in their tracks, but he can also release his stored heat in an explosive blast.
One-shot villain Icy Mike, for whom Empowered's boyfriend, Thugboy, once worked.
Arctica Lagopus from the series The Extinctioners, an Arctic Fox with Ice powers. Didn't see that one coming.
Dr. Frost from Prize Comics had ice powers and would encase himself in ice to survive explosions.
The Powerpuff Girls: In "No Business Like Snow Business" (DC run, issue #39), Mojo Jojo corners the market on winter goods and in the middle of summer creates a blizzard in Townsville. His weapon is a Zamboni with a snow and ice cannon.
