I've actually drawn a bunch more of the Fiend Folio do-overs but the drawings aren't near my scanner at the moment. However, for the sake of stocking my own dungeons I'm going to just list off all the changes I've made or am planning to make to the Fiend Folio monsters now. Hopefully I'll get around to scanning and drawing them later.
Mantari: A sort of fat land-crawling (not flying, not swimming) giant manta. Elephantlike skin.
Meazel: A meazel is the result of a kind of disease transmitted by a certain kind of goblin, it turns one of your fingers into a demonic biting monster.
Meenlock: I drew this and can't remember. I think it was some kind of psychedelic vertigo-inducing giant-head monster.
Mephit: original Folio text: "...they will wear clothes of the most garish design and color possible." Kinda like an evil leprechaun with funny hats, smoking pipes, looking like a demonic Mad Hatter.
Mezzodaemon: Oh I made some disturbing thing for this. Can't remember.
Mite: Can't remember.
Necrophidius: Left it alone, just redrew it.
Needleman: Did it as a humanoid with narrow 20-40-foot bent-back legs terminating in needles.
Nilbog: Largely as-is, but as a sort of goblin-magic-created champion.
Nonafel/cat o' nine tails: nine panthers with one (sentient?) brain. A schemer.
Norker: can't remember
Nycademon: can't remember
Ogrillon: can't remember
Osquip: Ecologically the same, only it's got no real head and a four-way flowerlike opening where the head should be like the Predator's mouth.
Penanngalan: Like a Vargouille but it doesn't fly, it walks using its entrails and casts spells as a witch.
Pernicon: It's like the Caterpillar in Alice but doesn't speak. Just gestures, offers tea. etc.
Phantom stalker: It actually stalks phantoms. A witch hunter or cleric that has undergone necessary rituals to be able to directly touch the undead. makes them nuts.
Protein polymorph: fuck this thing. ok, fine. A Protean is a giant-sized monster that's been verrrrry slowly turning from one thing to another over the course of 200 years. It'll be in some half-state. or half-made by the gods.
Quaggoth: No, "Othuagg". Like those long-nosed Guinea Babboons but goblins take them and dye them and drug them and make their hair and spike them up like John Blanche's Brat Gang pics from the original Confrontation 40k game and send them to kill you.
Quipper: You know those fairy tails where someone catches a fish and it asks them riddles or whatever? That's a quipper.
Qullan: Kinda like the original, only all female and Amazon and crossed with Mulan.
Retriever: It's the size of a normal spider. It crawls into your ear and whispers to you that you need to come with it to hell.
Revenant: A Kafka-esque soulless husk of a person--performs duties it had in life anyway.
Rothe: It's a mopey livestock creature that's sat in the same place so long that lichen and mold has grown on its back and the mold's gained intelligence and they have culture and whatnot.
Sandman: Basically the same. Only they wear clothes and disguise themselves.
Scarecrow: Better picture.
Screaming devilkin: its a gargoyle that's stuck in one place like the carved ones at Notre Dame. otherwise the same.
Shadow demon: "Demon's shadow"--if properly severed, at the right moment, a demon's shadow can be a useful servant or a terrfying opponent.
Sheet ghoul/phantom. Burying someone in a sheet that certain acts have been performed upon brings them back undead.
Skeleton warrior: like a regular skeleton but covered in mystic clay that makes it look like a human at first, the clay is carved with runes and shit and dyed in blood, slowly strips away as the champion takes damage.
Skulk: kinda the same, obscurely depressing.
Slaads: pretty much the same. at war with the chasme.
Snyad: "Dyad" Siamese twin goblin warriors, sometimes strapped into the center of giant spikey gyroscope-like spheres and rolled toward foes.
Son of Kyuss: This is a tiny lich made from a child prodigy evil cleric.
Stunjelly: you slather it on you and then attack. if you're nuts.
Sussurus: it is more abstract, and it can be bent into specific shapes to enunciate specific spells by powerful druids. kinda like the thing in Death Frost Doom.
Svnirflebenfm or whatever: the deep gnomes are just emaciated dwarves who have stared too long into he secrets of the earth. become totally insane, primitive, obsessed with lovecraftiana. bad earth magic.
Symbiotic jelly. It's just a sort of alien goo that gets on monsters and parasitizes them and makes them hungry. Makes creatures tougher and more hostile. also acts as stunjelly. stunjelly is actually dead symbiotic jelly.
Tabaxi: "Baxat" is what while-leopard men call themselves.
Tentamort: I love you just the way you are.
Terithran: another goblin weapon of war: weak, cursed goblins shoved or thrown across battlefields by their fellows whose touch causes specific terrible effects (cause light wounds, etc.)
Thoqqua: It resembles a very large tongue.
Thork: A trap laid by the redone aaracockra. looks like a stork but is full of scalding water.
Throat leech: a circular, toothed leechmouth appears on the victim's neck. makes it hard to eat and talks. like "the man who taught his asshole to talk"
Tiger fly: goblin bioweapon-- so-called because their bite marks foes with stripes--identifying them as enemies of this or that tribe of goblinkind.
Tirapheg: basically the same, improve the mechanics a little.
Trillloch: goblin espionge tool: Takes the form of a human woman who urges her husband to kill political rivals and their wives. The trilloch then eats the dead wife and changes to look like the dead wife, then urges the wife to kill various rivals, on and on forever etc.
giant troll, giant 2-headed troll, ice troll, spirit troll: these trolls are ordinary but insane trolls obsessed with pointlessly vexing the entity in question. a two-headed troll is a troll obsessed with bothering a pair of heads. a spirit troll seeks to depress people, etc.
Tween: A "Between". Takes the form of an ordinary animal. Often a black cat. Transfers bonuses from a PC's companions to him/her. A divisive opportunist hoping for murder.
Umpleby: an imp that preys upon small-time politicians. explains things to him about how things should go. greedy.
Urchin: "Emperor urchins" 15' in diameter. They roll across desert. Like Baron harkonnen crossed with a spiny ball. They roll and threaten.
Vision: a hallucination but the more creatures that believe it the realer it becomes. more and more hp.
Vodyanoi: Like an emperor urchin but it lives in rusty water and is made of rust.
Volt: a squat steampunk golem that delivers a jolt.
Vortex: another steampunk device--interlinking ring device with hula hoop-sized hole in the center, sucks you in.
Whipweed: tentacles that grow like long grass in huge vast plains.
Witherstench: just a "wither"--a bent, gruesome skunkperson
Witherweed: or Witchgrass. Its the stuff surrounding the witch on the cover of the first Sabbath album. touching it causes things to decay faster, burning it release the spirits beneath.
Xill: similar, but alien, not ethereal. and no legs.
Xvart: they are to goblins what Dwarven Trollslayers are to WFRP. Fanatical, dyed maniacs. Dyed blue.
Yellow musk creeper and its associated zombie: "Violet Leopard Orchid and Leopard Orchid zombie"
More encyclopedic monster goodness:
-Someone has decided to few the whole Manual from Pants this is a Catoblepas...
-Then there's this classic.
-And if you've got 18 minutes to download something, check this monster out.