Mr. Blizzard

Mr. Blizzards are living Snowmen in the Mario series that hop up and down and throw snowballs.

Super Mario 64
In Super Mario 64 and Super Mario 64 DS, they are found in Cool, Cool Mountain and Snowman's Land. They can be defeated by running around them, just like Mr. I. In the remake, Wario can defeat them with one punch and Yoshi can melt them with fire breath while under the Power Flower's effects.

In Super Mario 64 DS, as with many of the enemies, their look was updated, though their attack pattern remained unchanged. They now have a zigzag mouth, wear a blue bucket and have an yellow mitten instead of a yellow one with a single pink stripe. Their faces resemble those of Freezies.

Mario Pinball Land
In Mario Pinball Land, they appeared as one of the many residents of Frosty Frontier. This time, they don't hurl snowballs and unlike many other enemies in the game, they can't be defeated simply colliding with Mario.

Dance Dance Revolution: Mario Mix
In Dance Dance Revolution: Mario Mix, Mr. Blizzards are found in Freeze Mountain.

Mario Kart series
In the Mario Kart series, they usually appear as obstacles, but are often replaced with generic Snowmen.

Mario Party series
Mr. Blizzard's first appearance in the Mario Party series was Mario Party 3. In this game, they appear as a battle partner. As a battle partner, Mr. Blizzard has 3 HP and 1 attack point. His special ability allows him to always hit the farthest target.

In Mario Party 4, they appear in the minigame Mr. Blizzard's Brigade, now with a giant version which throw bigger snowballs.

In Mario Party 5, Mario Party 6 and Mario Party 7, Mr. Blizzards appear as the Mr. Blizzard Capsule. When an opponent lands on the space with the orb, a Mr. Blizzard falls on the player, causing them to lose all their orbs.

One Mr. Blizzard appears in Mario Party Advance, at the Ice Stadium. He is practicing his pitches when the player arrives, and he challenges the player to hit a home run. The player has five chances to hit a home run, and if this is done, Mr. Blizzard rewards the player with the Gaddget Mini Slugger. The ending states that he is practicing throwing a fastball in the minor leagues.

In Mario Party 8, Mr. Blizzards appear in the minigame Alpine Assault. Their only purpose is to obstruct the player.

In Mario Party 9, only two Mr. Blizzards appear, larger than their past incarnations. They are in the minigame Snow Go, in which they attack the player by tossing snowballs at them. Getting hit by a snowball results in the player being frozen. In the Museum, a constellation called Cold Guy based on the snowmen can be purchased.

Paper Mario: Sticker Star
Mizzter Blizzard, a Mr. Blizzard wearing a Royal Sticker, appears as the boss of World 4 of Paper Mario: Sticker Star.

Trivia

 * It is possible that they're related to the Dr. Freezegoods of Super Mario World 2: Yoshi's Island. Also, a Super Mario 64 character known as Headless Snowman resembles them.