Golem
Golems are creatures from Jewish mythology, animated humanoid creatures made from inanimate material (typically clay) brought to live by holy words (or Chem) by rabbis who, through their piety, gain some of God's power and knowledge, including some of that which he used to make Adam. Purposes for making a golem include general labor, labour in hostile conditions, defending treasures, places and tombs and killing the fuck out of antisemitic mobs. Comparable myths about animated statues can be found in other places, for example the Greek God Hephaestus creating gold and silver maidens to help him out, being crippled and everything (also to have sex with because his wife was a huge cheating slut, as were all Greek Gods). The word "Golem" has become a catch all term for such things.
Not to be confused with Gollum or the Pokémon Golem.
Golems in Dungeons and Dragons
In D&D, Golems are mid-tier enemies. There's about as many kinds of Golem as there are things out of which you could potentially make them, from quasi-robot Steel Golems to quasi-Frankenstein's Monster Flesh Golems. You could even use clay, if you're the kind of person whose pet tortoises die of boredom, though they do have some unique abilities. (Chiefly, hasting themselves and having a chance of going berserk.)
They are generally rather like fantasy-equivalents to robots, mindlessly following the orders of their masters to the letter rather than the spirit. They tend to have lots of raw strength and hit points, on top of high damage reduction and magic resistance (or even immunity) as a racial trait. Some of the more-exotic types have magical powers. Warforged are the closest thing to a PC variant golems possess.