Golems come in 4 varieties, Flesh, Clay, Stone, and Iron. They are notable for being immune to many effects, much like slimes but at a higher difficulty level, but with less counterplay.
All come with a requirement of spells, level of magic user, and cost in GP per HP of the golem to create one, which is interesting and suggests creative use of spells and spell combos being something magic users can do to create thematically appropriate magical effects outside of the normally very rigid conception of what spells can do. All (Save for the clerical Clay variant) have a rather inexplicable blind spot in that they also require a Wish spell which is beyond what the required minimum level of spellcaster could actually cast.
Clay Golems- The clerical variant of golems, they are extra-immune to weapons, requiring blunt magical weapons to hurt them. They are immune to spells save for Move Earth, Disintegrate, and Earthquake, all of which briefly slow the golem and harm it decently. They can haste themselves after at least 1 round of combat for 3 rounds, attacking twice for 3d10. They also have a 1% cumulative chance per round of combat to be possessed by a chaotic evil spirit and going permanently berserk and murderous. They also have but 7 AC, which makes them pretty easy to hit, if not to harm. On a final mechanical note, the wounds they inflict are accursed and require basically the highest level of cleric to heal.
This is, of course, a reference to the Golem of Prague, though the mythical counterpart has a more solid reason for going berserk. It acted as a protector of the Jews, but one day, when the Rabbi forgot to deactivate it to allow it to rest on the Sabbath it went berserk and showed up on a rampage while he was reading the very Psalm denoting the Sabbath as a day of rest and praise to god (Clay golem more like Irony Golem amirite). In any case, this berserker state seemed to have been induced not by a random chaotic evil spirit being allowed to just yoink a 50,000gp gold investment from a mighty servant of a Deity, but as punishment for violating the laws of god, no doubt as a moral lesson of sorts.
The story also gives a good weakness to the Golem- removing the shem (a clay tablet bearing the name of god) from its mouth caused it to deactivate. Far more interesting than requiring some very specific earth-based spells or having the warriors dig out their less-favored Maces +1 that languish in their packs, spurned for fancier talking swords.
Flesh Golems-Vaguely Frankensteinesque, but only if you didn't actually read Frankenstein, but maybe saw like, Frankenstein vs Dracula at a 1970's drive in or something.
They are uninteresting monsters, immune to nonmagical weapons, with terrible AC, decent offense in 2 2d8 fists, an ability to break down doors and wooden structures, and a similar berserk chance, but with a 10% chance per round for its creator to regain control. Fire and ice slow them, electricity heals them, and other spells have no effect.
The role of such monsters, I would presume, would be not to defeat conan types, but a sort of mage-hunter monster, or perhaps a bodyguard against rival wizards.
Iron Golems- The most powerful golem, they have AC as plate, can destroy structures with time, breathe small clouds of poison gas once every 7 rounds (save or die, one assumes) can only be hit by +3 or better magical weapons similar to some of the spicier demon lords, and are very immune to magic, being slowed by lightning and healed by fire.
They are, however, 'subject to attack by rust monsters' which is a nice specific weakness to have.
I have no idea what the poison breath refers to, as only mythological 'metal golem' I can think of is Talos.
Stone Golems are basically just lesser iron golems, busting out a single-target Slow every other round, being affected by +2 weapons, and rock to mud which slows them, mud to rock which heals them, and stone to flesh making them vulnerable to normal weapons for 1 round.
3.5 Golems are basically true to their original counterparts, but Clay golems are given 'healed by acid' and all golems are given very good AC scores in comparison to their original pitiful AC.
BFRPG drops some of the esoteric abilities, increased the ACs, and added a bunch of esoteric lesser golem types like wood golems which are basically killer mannequins, amber golems that are lightning-shooting lions made of amber, 4 armed sword-wielding bone golems, and similar things that are more interesting than what they did with the default golem types for sure.
Golems, I believe, are intended to be a threat that forces a return to physical problem solving, as they are immune to spells, but are fairly slow and stupid. They are fairly killable if you have the appropriate magic weapons and strong fighters, but hit hard enough to make melee an unpleasant prospect. The clay golem is unquestionably my favorite, as its cursed wounds discourages casual engagement and its mythological roots are stronger and richer than the other variants which come across as a blander set of scaling 'powerlevel' threats more than beings with their own identities.
Sunset Realm Golems
Mokkhus, God of Death, adopted brother of Riikhus and the other face of the Stone Sun, the Counter of Bones! The faithful do not seek to cheat death, but sometimes, the Gatekeeper of the Dead used a loophole and allowed an ancestor spirit to return to the realm of the living with the following restrictions.
1- The animated vessel must be inanimate, not a corpse (Wood being an edge case that was allowed) and clearly resemble the animating soul so as to avoid deception.
2- The soul can only return for the completion of a task, then returns to the underworld
3- Tasks must be aligned with the holy interests of Mokkhus, not mortal whimsy
A simple wooden mannequin was the most affordable golem, with a hollow suit of bronze armor the next. After that, a statue was the next most common option- a statue of wet clay could be remodeled to suit multiple spirits, or a statue of fired pottery could be a more permanent option. Stone was the most desirable, but even with the power of the god assisting, a spirit would have to be mighty indeed to move a stone statue, and so stone guardians only defended High Temples and other vital areas. The secrets of Golem-Crafting were guarded well by Mokkhite Priests even after the vanishing of their god and the obsolescence of their religion, and the process, while once almost standardized, is now ludicrously expensive, requiring ancient artifacts of the dead god to channel remnant power, and of course, a Golem Manual to describe these lost rituals and to find an appropriate spirit.
Everything has a soul, so modern-minded sorcerers simply anthropomorphize the soul within the materials of a golem itself and bind it. As elementals are tremendously dangerous at even moderate sizes and typically utterly unconcerned with anything humans are interested in, these magics tend to be highly complex affairs requiring dozens of Spellwisps to wrangle an elemental and absurd amounts of pure gold for interior runic bindings, but the process is exponentially cheaper and easier with smaller golems, as errors are unlikely to have serious consequences. Though unfeasible for middleweight bouts for all but the mightiest magicians, there is a thriving market for golems built for the Featherweight division of Beast Battler circuits- golems made of pebbles, candles, butter, root vegetables, and so on.
Popular in the 3rd age, and perhaps the inspiration for later variants, golems created by the unparalleled magics of the Alves are controlled by custom-made spellwisps of ancient and terrible power, with wide-range counterspell suites to prevent rival fey from breaking their expensive toys. They are more akin to magical robots, with personalities pleasing to their creators, and a high degree of personalization, as each was essentially a vanity project. It would be futile to talk excessively of them as a group, for apart from the mastery with which they were created, each was unique. Many persist to this day, their masters long vanished into the dreams of trees, ice, and the Iron Moon, their forlorn creations still fulfilling ancient dictums in broken ruins. An intact Alvish Golem is usually less a threat and more an opportunity to adventurers and archaeologists- if the golem's rune-logic can be understood, it can be utilized for the benefit of those who discover it.
When it comes to stitching together corpses before animating them, there's two main types of necromancers- the ones who want a giant unstoppable monster to rampage about with but all they have to work with is like, a local village graveyard, so they work with what they have, and the sort that are stitching together the dead to make a companion. Someone who has forsaken (or more likely been forsaken by) polite society to hang out with Corpse Dolls and Patchwork Girls of their own make.
Both these sorts of necromancers tend to blame each other for their own misunderstood unpopularity, while completely missing the point.
In any case, the only real difference between a 'zombie' and a 'Flesh Golem' is the amount of spellery put into one. A 'Zombie' is usually animated very simply by ravenous insect souls or fragments of nightmare, a 'Golem' is usually entirely spellwisp-motivated, and human-souled corporeal undead, regardless of the precise details, are usually called Revenants as a way to distinguish them from the 'nigh-mindless minion' variety. the more predatory human-derived entities like Wights, Mummies, Vampires, Ghouls, etc, and from the religious revenants of the goddess of undeath, the Children of M'shesh.
Clockwork Golems, or rather, rambling on the lack thereof in the sunlit world
Clockwork was well suited to dungeon machinery, the tech itself coming from a Stonefast 4, a now utterly-destroyed deep-delve fortress near the human city of Annu Nki that was known for its stone boats before clockwork was invented or unearthed by Svart 45045. By the late third age, dwarves were building their subterranean tricks and traps to both defend and increase the standard of living within their fortresses and outposts, and selling commissioned devices to those who could pay their prices, and so antique clockwork is a common enough discovery for tomb-robbers, especially in the north moonlands near Limedike and Annu Nki.
The idea of a clockwork golem complex enough to operate independently or even semi-independently was an amusing 'idea bounty' among dwarves for a time, though it never went anywhere. Amusing automata yes, wind-up toys and clocks, of course, but clockwork alone simply wasn't complex enough to operate reactively. This branch of research was further crushed by the geopolitics of the third intersolar period and the 4th solar age. Wracked with magical catastrophe from the fallen Elf hegemony, neither the Witch-Queens of initial post-elf human rule nor the later conquest by theocratic Riikhites had much use for the idea of clockwork, being intensely magic or piety-focused, respectively. And so the field of clockwork became largely an abandoned one, eclipsed by runic magic developing first with the aid of the Witch-Queens, and Mokkhite golem-crafting later once dwarves once swore allegiance to the Stone Sun pantheon of Riikhus, Mokkhus, and the other enslaved deities.
During the 4th intersolar period, the majority Riikhite/Mokkhite population of dwarves, in a panic due to the death of their prime gods and dissolution of the Stone Sun pantheon, became fearful that their devices might be turned against them and used to oust them from their otherwise invulnerable stone fortresses by the human masses seeking refuge from the onslaught of Moons and Darkness outside. In exchange for granting refuge to the ruling nobility, clockwork and gunpowder not in dwarf-hands were outlawed by the Mercian Empire in perpetuity, and this law was retained among the splinter-states that formed as the Mercian Empire collapsed without its theocratic unity. The old law, devoid of context, nevertheless lined up with the desire for nobles to prevent guns from developing enough to challenge knights, and so despite the laws of Mercia no longer applying to places like the Fault or the Tripartite Realm, the clockwork/gunpowder ban remained almost worldwide for several hundred years, with Saresare and the Beast Islands being notable exceptions.
While by now dwarf society was well into its inevitable decline due to the gnawing darkness at the roots of their stonefast fortresses in the 5th age, the dwarf Thirbaek Merrymace(PC from the last 2.5 campaigns I ran), before he was father to the 6th sun Aurum or Underlord of Stonefast Two, brought back a titanic war machine from the Moonlands- the Keeper of Days- or rather, an unfinished replica of the Keeper, as the original was destroyed in the Oroboro Civil War by the Serpent Queen supporter Erhard De Vend- but I digress. It had no will of its own, requiring a pilot, but the dwindling population of the dwarves suddenly had incredible force multipliers in the form of these Keepers, where a lone pilot could become a 60-foot colossus of ticking steel. The Keepers spread throughout dwarf society and allowed them to reclaim land lost to the Moonlands and fortresses lost to chaos, and seem to be a herald of a new dawn for the dwarves- though if the temptation to use gunpowder proved too great for humans to keep to the pact, surely these metal titans will likewise lead to the loss of the old ban.