Snow Golem

A Snow Golem is the game's first "utility mob", defined by Notch as any player created mob. Snow Golems are created using Pumpkins and Snow Blocks. Snow Golems will throw snowballs at enemy mobs and will melt in warmer Biomes. In cold biomes, they will not melt even when lava is near them, unless they fall in it. As Snow Golems move, they leave a trail of snow on the ground (but not in deserts or in the Nether). Snow Golems will not leave snow over blocks such as Redstone dust or torches, but they will wreck farmland by walking on it, and then put snow on the dirt. Once killed, the Snow Golem will drop 10 snowballs.

History
The Snow Golem (previously and colloquially known as a Snowman) is a mob which was first mentioned by Notch on September 21, 2011 to appear in Beta 1.9, but now officially appears in Minecraft 1.0 since the 1.9 versions were all Pre-releases.

In The Story of Mojang, Notch briefly mentioned about adding "snowmen that throw snowballs."

Notch originally planned to call this mob Snowmen. However, very soon after revealing the name, he came upon an entry by the Reddit user "Cuttleman" stating he would call them Snow Golems. Notch immediately decided to change their title to this.

Behavior
Snow Golems will throw snowballs at hostile mobs, provoking them. This gives them an almost suicidal nature - snowballs do not do significant damage, but they attract enemies which can kill it or the player. In Beta 1.9 Pre-release, Snow Golems sometimes forget to attack monsters. Snow golems have good pathing skill; they will not attempt to jump off cliffs or into lava. They will attempt to path towards hostile mobs, and even go through open doors to reach them. As of 1.0.0, Snow Golems can now open doors.

Creating
To create a Snow Golem, the player must vertically stack two Snow Blocks on the ground, then place a Pumpkin on top of it. They are not made on the Crafting Table. They are only created when the pumpkin is placed last. Pistons cannot create Snow Golems because they cannot push pumpkin blocks. Snow Golems can also be created using a Jack-O-Lantern, although there is no visual difference. Endermen are also capable of creating Snow Golems by placing the necessary blocks, although this is extremely unlikely to occur naturally. As well, if the snow blocks and pumpkin were placed in 1.8 or earlier versions, they will not become a snow golem upon updating.

Farming
Because Snow Golems leave a constant trail of snow as they move, it is possible to farm that snow. However, due to their behavior of attacking hostile mobs, it would be wise to ensure the Snow Golem is in an enclosed, safe place before beginning. The simplest method is to create a 1x1 hole that is 2 blocks deep, and to put both the player and the Snow Golem in. Then the player would look straight down and farm the snow that is produced. This creates an infinite amount of snow in the shortest time possible, because the instant the snow breaks, another one spawns in its place.

Defense
A horde of Snow Golems kept between two lines of fences provides a wall that keeps mobs at a distance. The Snow Golems will still be killed by Skeletons. A 1x1x2 area can be used to store a horde of Snow Golems. In an emergency the Golems can be released to push back an approaching enemy. Also efficient is putting Snow Golems In "Guard Towers" up in the air, to keep certain mobs from damaging the Snow Golems. To create a guard tower, make a small 3x3, 1-4 block high tower. fence in the top and create a Snow golem in the center.

Lure
Snow Golems can also be used to lure hostile mobs into traps intended for them. This can create a better flow of mob drops for the player to collect, speeding up mob harvesting. This can be something such as fencing in Snow Golems just beyond the trap's entrance, having the mobs wander in as they attempt to attack the Snow Golems and dying.

The player can also fence in multiple Snow Golems 2 wide above a pit of lava 2 deep. As this won't melt them, they will be free to provoke mobs into falling into the trap, passively protecting the player's work area. These methods can also keep mobs from hiding around the player's home.

A single Snow Golem kept between four fences under a 3x3 two blocks high ceiling can be used to distract attacking Endermen. Once the Enderman is within reach of the Snow Golem, the Golem will pelt it with snowballs. The Endermen will stop attacking the player, but will be unable to reach the Snow Golem due to the ceiling. A moat filled with lava or water around the Snow Golem enclosure can be used to kill the Endermen instead of simply distracting them.

Distance Triggering
By placing a Pressure Plate inside the fenced area mentioned above, the Snow Golem can be used to activate traps as well. Note that Creepers, Spiders, Cave Spiders, Skeletons, Spider Jockeys, and Magma Cube traps are not advised for this.

Bugs

 * Snow Golems do not leave snow trails in Mushroom Biomes.
 * Snow Golems can be built in The Nether. This would not appear to be intended, considering other forms of water either melt or evaporate there. However, blazes may be killed by snowballs.
 * In SMP, Snow Golems do not make a sound when throwing a snowball.
 * In Beta 1.9 Pre-release 2, Snow Golems will start attacking the player if he/she holds Wheat. This is presumably because Snow Golems might have the command to attack within their follow command, and the new Breeding system makes "passive" mobs follow entities. This also applies to their being in Love Mode; whereas they will begin following each other and cause themselves to attack, thus disabling their Love Mode and causing them to flee from one another.
 * In Beta 1.9 Pre-release 3, in SMP, Snow Golems have become invisible but were still able to be killed. This was fixed in Beta 1.9 Pre-release 5
 * In Beta 1.9 Pre-release 4 however this is partially fixed. However it doesn't seems to be working in the End
 * In Minecraft 1.0 snowgolems can multiply if place in a small tower, this bug is common for those who build snowgolem towers.

Trivia

 * A couple hundred snowmen can in fact kill mobs, but will understandably take quite a while and result in heavy losses.
 * Snow Golems are the second mob the player can spawn themselves. The first one is Chickens spawning from Eggs thrown by the player.
 * Four Snow Golems throw snowballs at a fast enough rate to continuously push a Zombie back.
 * On Reddit, Notch stated that the Snow Golem is the first "Utility Mob"; a mob that the player can create for their own convenience.
 * Snow Golems are not affected by fall damage. It is unknown if this is a bug.
 * Snow Golems wear their Pumpkin as a hat. Their actual Snowman-type head is hidden beneath it.
 * If a Snow Golem is lit on fire, it will speed up and move toward a water source.
 * Snow Golems do not attack aggressive wolves even if they attack the player.
 * Snow Golems will attack Zombie Pigmen regardless of whether or not they attacked the player, thus making the whole pack attack them.
 * Snow Golems sometimes survive creeper explosions.
 * The throwing sound is actually the Bow firing sound, even though Snowballs have their own throwing sound.
 * Snow Golems don't leave a snow trail in the nether.
 * If a Snow Golem is trapped somewhere and there is an exit, the Snow Golem will try to escape, immediately heading for the exit.
 * Snow Golems do leave a trail of snow in The End.
 * Since the full release, (1.0) Snow Golems no longer have the ability to breed. This is possibly due to the fact the snow golems attack each other when in love mode.
 * Snow Golems can only be crafted by placing a pumpkin on top of two snow blocks, placing the pumpkin then snow under it will result in failure.
 * If trapped underwater, Snow Golems CAN drown, despite not being alive.