Iron Golem

Iron Golems are creatures which appear throughout Mojang's Minecraft franchise.

Description
An iron golem appears as a large humanoid monstrosity, half again as tall as a man and made from, as their name suggests, solid iron decked in hanging vines. They have an unusual face with a large nose, both of which are very reminiscent of their beloved villagers.

These beings may manifest in two different ways in a Minecraft world. Firstly, they will spawn naturally in villages which contain at least ten villagers. Secondly, it is possible for a player to create one by placing four blocks of Iron in a T-formation capped by either a pumpkin or Jack O'Lantern. This second way is useful for creating situational guardians, but is relatively resource-intensive when manufacturing larger numbers of Golems due to the fairly high count of Iron Ingots required to create an Iron Block.

Once deployed, an iron golem will patrol the village it was birthed in, engaging any mob or player which "provokes" it. Iron Golems which are not in a village will simply wander the countryside aimlessly. An iron golem will be provoked if either a) it is itself attacked by another entity, or b) a nearby villager is attacked. Once provoked it will move quickly towards its target and swing its long arms violently upwards, causing massive damage and flinging the target high into the air. This attack is the third most powerful in the game, outdone only by the explosions caused by Creepers and Charged Creepers. They may employ this attack even through solid objects and without line of sight to their opponent, making them even deadlier to an unwary enemy.

Incredible Strength
As mentioned before, iron golems possess an incredible level of strength, being potentially able to "one-shot" a player with their powerful attack.

Immense Durability
These creatures are capable of absorbing an immense amount of punishment, being very difficult (although not impossible) to kill.

Damage Immunity
While an iron golem will effectively "shut down" when immersed in water, they are completely immune to drowning damage. They are similarly unaffected by damage sustained by falling from height.

Trivia

 * Iron Golems are known to occasionally offer a gift of a poppy to villagers, as a symbol of their love for their charges.