Lapidarians

Lapidarians are a "race" of mobs that are all similar:  they are all large rock creatures that look like knights.  Similar to iron golems, they smash with their fists, and pick up and throw players.  There are three types of lapidarians:

The mountain lapidarian spawns on mountains and is hostile towards players.  It often stays at the peaks of mountains to ensure that players cannot reach it.  It is made of stone blocks.  In snowy biomes it can have snow on top of it.  

The cave lapidarian spawns deep in caves and is hostile towards players.  It protects precious loot of diamonds.  Its presence is also a sign that there may be diamonds nearby.  It is the smallest lapidarian and is made of stone blocks.

The infernal lapidarian spawns in the nether and is rarer than the other two lapidarians.  It can be found in nether fortresses around loot.  It is the largest, strongest, and most hostile of the lapidarians.  Instead of normal stone, it is made of magma blocks.