Where created by the player
Snow Golems are the game's first utility mob, which Notch defines as any player-created mob. They are friendly to their creator. Snow Golems are created using pumpkins and snow blocks, and will throw snowballs at enemy mobs. As Snow Golems move, they leave a trail of snow on the ground, except in Plains, Beaches, Swamp, Mushroom Island, Desert, and Jungle biomes, and the Nether. If a Snow Golem walks over a mushroom, the mushroom will be destroyed and dropped as an item. Snow Golems do not take fall damage. Once killed, the Snow Golem will drop a maximum of 15 snowballs. Like Endermen and Blazes, Snow Golems take damage upon contact with water.
To create a Snow Golem, the player must vertically stack two snow blocks on the ground and then place a pumpkin on top of them. A Jack 'o' Lantern can also be used instead of a pumpkin, but this has no effect on the snow golem's appearance or statistics.
Players should be aware that Snow Golems cannot be made on the crafting table, and are only created when the pumpkin is placed last. Pistons cannot create Snow Golems, as they cannot push pumpkin blocks. Endermen are capable of creating Snow Golems by placing the necessary blocks, although this is an extremely rare event because they do not do so deliberately.
Snow Golems throw snowballs at most hostile mobs up to 10 blocks away  provoking them. This gives them an almost suicidal nature, as the thrown snowballs do not do any damage, except to Blazes and the Enderdragon. Snow Golems do not attack creepers, aggressive wolves, slimes, or magma cubes. Note that in Xbox 360 1.6.1, they WILL attack creepers, which will then approach and explode, so be careful placing Snow Golems near your structures. They will attempt to move towards hostile mobs. Snow Golems attract enemies and do not follow the player, making them useful for luring enemies into traps. Snow Golems have good pathing skills, and will not jump off cliffs or into lava. Snow Golems "melt" (take damage) in Deserts, Jungles, the Nether, and when in contact with rain or water. Snow Golems are also useful for dispatching Endermen, as the snowball will make them teleport away.
Snow Golems are also able to be pushed up ladders; they are able to climb as high as one square naturally as well. (This is similar to Iron Golems.)
A Snow Golem's primary purpose is to defend the player from mobs. Four Snow Golems throw snowballs quickly enough to continuously push a zombie back. Due to their small health, however, players are advised to use many all at once. Snow Golems will attack Zombie Pigmen regardless of whether or not they attacked the player, thus making the whole horde attack them.
Since pumpkins can be found in Taiga biomes, it may be a nice idea to build a few Snow Golems when first starting out if one is desperate.
Here are a few examples of efficient ways to defend yourself and your valuables:
A horde of Snow Golems kept between two lines of fence provides a wall that constantly pushes back mobs at a distance, and in an emergency, they can be released to push back approaching enemies. Another way is to place them into guard towers, shielding them from damage. To create such a guard tower, make a small 3x3, 1-4 block high tower. Add another block 4 blocks up from the center to protect it from rain. Surround the top with fencing and create a Snow Golem in the center. Don't use pressure plates in your shelter if snow golems will be around them. They are able to walk on them as it can lead to them running off.
Snow Golems deal no damage to most mobs, but Blazes are an important exception. Given enough splash potions of Fire Resistance, they can also be used to farm Blaze rods from Blazes.
Because Snow Golems leave a constant trail of snow as they move (except in Plains, Swamps, Deserts, Beaches, Jungles, Mushroom Biomes, and the Nether), it is possible to farm that snow. However, because of their habit of attacking hostile mobs, it would be wise to ensure the Snow Golem is in an enclosed, safe place in the 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 dig the snow layer beneath the golem. This creates an unlimited number of snowballs very quickly, because the snow layer regenerates as quickly as it is mined. A shovel must be used to collect the snow as snowballs -- with other tools or none, it is simply destroyed. (Note that the shovel will wear out quickly -- a diamond shovel will be completely used up in 2 minutes 30 seconds.) Since snowballs only stack to 16, they can quickly fill the inventory, but of course they can be condensed into snow blocks (which do stack to 64, and store 4 snowballs each). If one wants to farm snow in a Plain, Swamp, Desert, Beach, Jungle or Mushroom biome, the golem can sometimes be put on a platform above a lake or river, as they count as separate ("River") biomes in the code.
In The Story of Mojang, Notch briefly mentioned adding "snowmen that throw snowballs."
Notch originally planned to call this mob Snowmen. However, very soon after revealing the name, Reddit user Cuttleman stated he would call them "Snow Golems," a name Notch approved of and made official.
The inside of the Snow Golem's head is not a pumpkin. Instead, it is the original Snowmen head, a smiling face made of black pixels on a snow like background.
During the Beta release candidates, Snow Golems would attack players holding wheat. This is now fixed.
When breeding was released in 1.9pre2, Snow Golems could breed as well. This was a bug and was fixed in 1.9pre3.
As of Snapshot 12w06a, Snow Golems have a new path-finding AI and will form a wall to attack mobs.
As of Snapshots 12w07a/b, Snow Golems take damage in Deserts, Jungles, the Nether, and when in contact with rain and water.
- Snow Golems do not leave snow trails near bedrock, or on ice or glass.
- In SMP, Snow Golems do not make sounds when throwing snowballs.
- On the Xbox 360 Edition, only eight can be made at a time, but as of TU11 more(?) can be made.
- Snow Golems take damage from snowfall when playing on Creative.
- Snow Golems are called SnowMan in the game code.
- Although Snow Golems will attack most hostile mobs, they will only agitate skeletons, spiders, cave spiders and Zombie Pigmen. Endermen simply teleport away.
- Snow Golems wear their pumpkin as a helmet just like the player does. Their actual Snowman-type head is hidden beneath it. If the player occupies the same space as a Snow Golem, the Snow Golem's Pumpkin helmet will be seen through, revealing their snowman-style face.
- The throwing sound is actually the bow firing sound, even though Snowballs have their own throwing sound.
- Snow Golems can only be crafted by placing a pumpkin on top of two snow blocks; placing the pumpkin then snow underneath will produce no Snow Golem.
- If trapped underwater, Snow Golems can drown.
- Snow Golems do not create ice when moving onto a water block.
- Snow Golems cannot be made by pistons because the code for generating Snow Golems are found in the Pumpkins "OnBlockPlace" (When placed by a player) event, Also pumpkins will be dropped as an entity when pushed by a piston.
- Using a texture editor with the pumpkin texture invisible, the true Snow Golem's face can be seen.
- When constructing a Snow Golem, it will be 3 blocks high, but when it activates it becomes only 2 blocks high.
- Snow Golems and squid are the only mobs that do not make any sound (except when Snow Golems are attacking).
- Since the damage Snow Golems take in hot biomes is fire damage, a splash potion of Fire Resistance thrown immediately after the creation of one will make it survive. With redstone dust, this means around six minutes. In the Nether it will prevent damage from fire, lava and Blaze fireballs, but not Blaze contact.
- Snow Golems can be crafted unintentionally by Enderman if they are roaming around with a pumpkin and happen to place them on two snow blocks crafted by the player.
- Snow Golems do not leave behind snow when they move on the top half-slabs added in 1.2.5.
- Snow Golems were given path finding AI when they were introduced, making them the first mobs to have path finding AI.
- If a wall of Snow Golems is attacking a mob, the snow balls may hit other Golems thus pushing the wall forward.
- It is unwise to have an army of Snow Golems and Iron golems. If such an army is attacking a mob, Iron golems may be hit by snow balls from the Snow Golems and thus making the Iron golems hostile to the Snow Golems.
Three snow golems that were built by Endermen.
In a Zombie Pigman trap, a Snow Golem teams up with several Iron Golems to kill the Zombie Pigmen, giving the player gold.