d100 Familiars

This is intended to be system-agnostic. If your GM is chill you can get away with some of the more interesting ones. If you are the GM, be chill. 5e style familiars are super lame and boring—they are just magic pets anyways.

1. None. Your familiar has recently died. You are in search of a new one.
2. Robot eagle. Has arms in addition to wings. His bionic eye can see through up to 1/2" of any material.
3. Mummy frog. Can summon a very small and ineffectual swarm of 3d6 flies.
4. Changeling Cockatiel. Normally looks like a normal Cockatiel, but can morph into a 1' visage of anything its seen. Cannot imitate speech. Hardly useful as a tool, as it is very unreliable and tends to change into whatever it wants whenever it wants. Don't let it see anything you don't want it to imitate.
5. Cyclopean Cat. One-eyed. Has small tusks and likes to drink.
6. Animated sock puppet. Useless unless you commit one hand to its animation.
7. Miniature Chameleon Wyvern. Two wings and two legs. Curly grasping tail. Changes color with its erratic emotions, not to blend in. Often angry at you and you don't know why.
8. Tiny wooden knight. Cannot speak but is very loyal. Hops up and down and makes dramatic arm movements to get your attention.
9. Push Beetle. Size of a chihuahua. Crumples up all your scrolls into a big ball and pushes them around for you like a dung beetle. Really unfortunate familiar for muddy conditions.
10. Taxidermy weasel. Attached to a wood stand. Makes noises like someone who can't move their mouth. Its eyes dart back and forth. Moves when nobody is looking.
11. Crat. Rat with a cat-size body and rat-size head. Walks on two legs. 
12. Lard ooze. Can store things inside itself. Dissolves in water. No limit to its size (which is directly correlated to how much damage it can survive), but can only incorporate fats like lard or butter.
13. Eggball. A large egg with one eye and an audible heartbeat. Rolls around. Can cast invisibility once per day.
14. Mutated grasshopper. Has a human-like face. Can fly and slam into people as like a sling attack.
15. Masks. Two floating theatre masks connected by a red and yellow ribbon. One smiles, one frowns. They work together and can grab things with their teeth.
16. Animated broom. Like fantasia. Has arms.
17. Ape chair. A wooden chair with arms and legs carved like chimpanzee limbs. Can function as wheelchair. Causes you to look important, but not rich.
18. Two-headed crow. Will bring you odd shiny things (like coins.) Witches will try to trade you other, stranger, familiars for it.
19. Porcupine. It has one extra large arm deformed by dark magic. It may be intimidating to any foe smaller than a human.
20. Floating Porcelain eye. Does not blink or change. Can cause a slow-moving cancer not dangerous to anything with a lifespan less than 500 years.
21. Potted Lemon Tree. Grows 1d6 mundane lemons per year. Must be fed and watered. Cannot move of its own volition.
22. Red and Pinked Striped cat. Has all black fur on its head. Very sneaky. Does not make sound of any kind under any circumstances. Like, even if you were to hit it with a bat and crush its bones—no sound emanates.
23. Blonde unicorn. Regal.
24. Dog-sized tarantula. Vulnerable to piercing weapons.
25. Igor. Low-self esteem and loyal. Its really messed up of you to use a human as a familiar.
26. A small moon. It orbits you. It has minor gravity magic.
27. Articulated stone golem arm. Obeys the most recent command given to it by any creature.
28. Familiar Chain. An adamantine chain that makes any creature with animal intelligence act as your familiar as long as it's worn. Currently worn by a rottweiler.
29. Master goat. It has its own familiar, a raven. The goat will obey you but has its own machinations. You do not have any power over the raven.
30. Elephant Landstar. Terrestrial "sea"-star. Can crack locks with its powerful beak or grapple opponents like a pair of manacles. It craves eggs, and can't be persuaded not to try to eat any egg it encounters.
31. A floating skull, magically animated when a cigar is put burning in its mouth. Acts as if mundane otherwise.
32. A silver tongue on a silver chain. Tongue once belonged to a historian of magic. Speaks audibly and slowly. It has a great knowledge of abjuration and the history of great abjurers.
33. Praying mantis. Made of folded paper. Can fly. Can't swim.
34. Metal spider. It spins up to 50' of metal wire in its lifetime. It can eat its own metal wire to replenish its supply. (I had a recurring nightmare for a little while where I had a bug on me which always ended with me trying to crush it with my hand and being horrified to find it made of metal.)
35. Tiny cloud. Has a cloud-formed old lady face. Very wise. Encourages its master to be patient and careful. Can storm, but it isn't very powerful becomes fatigued.
36. Smoke troll. A great familiar. 2' tall gray bipedal creature who's skin constantly produces a thin smoke. It has almost dog-like facial features. Anticipates your needs and seeks to fulfill them, although it is not prescient. Doesn't like to talk—although it can.
37. Archaeopteryx. Very cool little feathered dino. This one has an advanced intuitive understanding of mathematics. It can guide your haggling with its subtle head nods and shakes, but only if the item you're haggling is interesting to it (food or shiny things).
38. Flea Golem. As strong as a man, as large as a bean. Only ever obeys 50% of what its commanded to do.
39. Vestigon the proper. An infernal imp with four arms and no wings. Can teleport short distances with a 30 second delay. It will try to (literally) poison your companions. You can sacrifice a level up to grant it two level-ups. The more powerful it is the less likely it becomes to obey you. 
40. Mole-rat. This creature can shapeshift between its natural form (a mole) and its lycanthropic form (a rat) at will. It speaks a language common in this world, but which you do not currently know.
41. Half-blind coyote. It can see into the spirit realm, but has poor vision of the physical realm.
42. Goblin badger. A large badger bred to hunt goblins. It has powerful burrowing claws and digs tunnels large enough for a man to crawl through on his belly.
43. Gem prince. A small intelligent golem which you are attempting to train for some great purpose. Like a Pinocchio. 
44. Artillery barnacle. Attaches to your skin. It can provide breathable air for you underwater. Its cannon's range is doubled beneath the waves.
45. Pufferforce Toad. A large toad which expands a globe of force around itself when threatened, blocking all physical beings, objects, and effects of low or moderate power strength.
46. Bloodthorn vines. A thorny plant which feeds on blood. It can grow into your veins, taking a small amount of damage you receive in your stead, but causing you vulnerability to fire. It wants to germinate its seeds in the corpses of your enemies.
47. Cobra fist. A snake with a left-hand instead of a head. Weirdly skin-colored. 10ft blindsight, blind beyond.
48. Coconut crab. Is intelligent but utterly utilitarian and without empathy. (Will attempt to eat your fallen comrades.) Can climb and grapple.
49. Magic carpet. Good sense of humor, vibrates at your jokes. Has a carrying capacity of 10lbs, and can't move while encumbered. 
50. Projection orb. Projects the blue hologram of a beautiful woman. She is moderately intelligent, but remembers nothing from one conversation to another besides generally who you are. Can record audio, with up to 40 seconds of audio storage.
51. Capuchin. Fiendish little monkey. Speaks the language of nobility. Refuses to wear any kind of clothing.
52. Hyena king. Participates in combat regardless of system rules. You need to employ its golden muzzle in populated areas to avoid it biting passerbys. 
53. Angelic skull. A golden skull with four feathered wings. Can always tell if a creature is living or dead. Sings a sorrowful lament at sunset.
54. James the owl familiar. He has secretly murdered his last 9 masters, and seeks a tenth. His hoot has a "villain laugh" quality.
55. Finger prophet. Large disembodied ghost of a hand. It writes its master's fortune on the wall each dawn (weal or woe, you can interpret this as a +1 or -1 to all rolls that day if you want.) It can grab incorporeal entities, but not corporeal ones.
56. Black rabbit. Can turn invisible at will, (useful for magic tricks.) Becomes dangerous if not well fed.
57. Bush-ent. Small awakened shrub. Can speak to plants on your behalf. 
58. Goblin slave. This goblin has, for some goblin-logic reason, determined you to be its master. You cannot get rid of it. It speaks of you like you're a terrible master no matter how you treat it. It will randomly turn your possessions and resources into wasteful and absurd inventions.
59. Vulture. Sneers at your enemies from atop roofs or fences. Will not help you if they might be put in danger.
60. The cube. A polished black cube which makes a humming sound as it floats through the air. It knows the exact age of all objects, and the identification code of the object's creator (kind of only useful for figuring out if two objects were or were not created by the same creator.) It is from the future, seeking to catalog things which no longer persist, in search of forgotten tech. It speaks of avoiding "young Vacuum Prime."
61. Canicore (dog-eater). A small chimeric creature with a bobcat head and arm, lizard head and arm, and a sea lion rear.
62. Koala. Has psionic powers, but anything it telepaths to you is communicated to all creatures within 30'. Any creature within 30' can see through the koala's eyes.
63. Darwinian Lockfinch. Semi-intelligent. If you place a treat inside a lock, it will morph its beak to fit the lock.
64. Two pits. These pit-bull twins are ferocious. Their sleek gray coats give you the air of someone to be respected. They will not leave each other's side, and if one dies the other one will quickly follow suit.
65. Giant Roly-Poly. Can roll up to protect itself (or so you can douse it in oil and light it so you can roll it into foes like a bowling ball from hell). Can climb walls that are the opposite of smooth.
66. Hammerhead Snail. Last of its species. They used their hard heads to break their rival's shells by whipping their outstretched heads against one another.
67. Bovine Machine Cultist. Small robotic shaman. Wears the preserved head of a cow as a mask. Performs rituals every evening.
68. Magic Mirror. Has no special knowledge, except that it knows if you are the most of or best at anything in the world. For instance, it can tell you if you are the most beautiful person in the world, or if you are the best tennis player, but can't tell you who is the best spaceship pilot unless its you.
69. Venomous Caterpillar. Normal caterpillar size. Venomous to the touch. Easy save or causes peaceful hallucinations and a disregard for consequences. Will one day metamorphose into one of the horsemen of the insect apocalypse.
70. Stilted Seahorse. Terrestrial seahorse with long, narrow, single-toed legs. No arms.
71. Greater Urban Amphipod. 3' long amphipod which moves through jumping short distances. It can burrow and can detect electricity.
72. Golden Retriever. Great wingman/lady and grants a small bonus to seduction rolls, if the target likes dogs. Also grants +2 versus mental illness. It has no combat instinct or ability, and there is a 10% chance you enter serious long-term depression if it dies.
73. Dimensional Exchange Familiar. These shloggy (a texture our 3 dimensional brains interpret as soft) creatures are 4-dimensional. They have various non-euclidian appearances depending on your opinion of it. They cannot eat anything native to this dimension, so they only hang around for about 3 days before leaving and being replaced with another of their kind—per your contract with their masters. They know a lot about interpersonal relationships and how to make peace with others, but always speak to you like an adult with no kids talks to little kids. Slow and sort of condescending. 
74. Scintillating Python. Mildly radioactive. Likes things as they were long ago. Often counsels you to delegate responsibility.
75. Throwing Grackle. Can throw its voice to sound like its emanating from somewhere else. Can imitate words but not voices.
76. Gnarled Baboon. Its infected with Papio Papillomavirus, causing it to grow hard, antler-like warts all over its arms and face. Its very scary when screaming and chasing things.
77. Grandfather Koi. Majestic beard of barbles. Can fly, but can't breathe outside water. It knows many old freshwater creatures on a first name basis.
78. Shale Gargoyle. Its natural, not carved. It's hard to tell if it has a face or if you are just imagining it does. It cannot fly on its heavy stone wings, but it can climb—leaping from one ledge to another, faster even than it can walk normally.
79. Pygmy Ostrich. Wears a wealth of gold bracelets and bangles. It's feathers are heavy with jewelry. 
80. PseudoBio Dragonfly. Made of nanites which imitate natural biology. It can fly extremely fast, but cannot carry anything. It can modulate its size to be anywhere from 0.5"–7" long.
81. Ported Goblin Shark. Deep sea goblin shark, in the deep see, but with a moving portal in front of its face so that it can sort of follow you around. Water does not fall out of the portal. You can put stuff through the portal for it to eat. Don't expect to get it back. 
82. Rune Cairn. A mobile cairn of runed rocks. It tumbles about in a pile. It can crush toes. It can glow as a torch.
83. Morphing Pig. Can move rapidly along the scale between being a show pig to being a wild boar, depending on its environment and circumstances. Moving from one extreme to the other takes 1 hour.
84. Ropetail Monitor. Monitor lizard with a detachable tail. Tail regrows 1' per week once detached, to a maximum of 10'.
85. Eel Jarrobot. Spindly robot body with a moray eel in a jar to control it. The jar looks very small for an eel of this size.
86. Undead Gorgon head. This decapitated zombie gorgon head has very weak petrification powers. I pulls itself across the ground with its zombie snake hair.
87. Glamour Pixie. Has a Brooklyn accent. Her hair is always dramatic and different. Can use Vicious Mockery, but against former allies only.
88. Bronzed Bear. This bear is extremely old and relatively frail, a remnant of a bygone race of bears. Its instincts are all that remain, even if its senses are dulled. It has good intuition about ambushes and where to find fresh water.
89. Leather dog fetish. A crafted stuffed fetish of leather, inhabited by a young and ignorant spirit. It is in the rough shape of a dog, but has no features. The spirit is seeking to know more about this realm. Give it a few hundred years, and it may become powerful enough to no longer need this physical form. While it may not know much of your physical world, it does intuitively understand much about spirit power.
90. Fish Priest. A 2' tall blue fishfolk priest. Its language is strange, but with the help of his prayers you haven't died yet. He seems to be on some holy mission, and you are a part of it.
91. Kookaburra. Good for creating distractions. Is wanted in two backwater towns.
92. Skeleton servant. Was once a child or a gnome? Does not have eyes, its vision is as one nearly blind (it does not have blindsight). You have painted its bones, and one day hope to commission your favorite artist to turn your servant into a masterpiece.
93. Demon worm. Not much use right now, besides causing your enemies mundane nightmares, but once it reaches its potential its loyalty will be priceless. It is very unlikely that it will just murder your and eat your bones instead of rewarding your sacrifice.
94. Stump. An animated tree stump (I think this makes it an undead plant?). It has tremor-sense, and can store enough water to sustain a man for 2 weeks. It is slow and heavy.
95. Tattooed owl. Used to be familiar to a necromancer, and it missing the feathers on its head and back. It uses minor necromancy chants to raise tiny bone shambles out of its regurgitated pellets.
96. Miniature Ankylosaurus. High AC/Parry. Can carry 60lbs without trouble. Very survivable, but a poor scout.
97. Stag Beetle. Larger than a natural stag beetle; cat size. Moves deliberately like an elephant, not the wild tapping feet of usual beetles. Its pincers can grapple, but the beetle is not heavy enough to restrict or hurt anything bigger than a poodle.
98. Baby Dragon Turtle. This is the beginning of its life. It will double in size every two years until it is the size of a city. If you go near the ocean it will abandon you.
99. Blind ghost. Is bound to you, and you are the cause of its death. It does not blame you, but you must complete some quest in order to free it. It cannot move more that 30ft from you. It can move through walls.
100. Reroll twice and take two familiars. They hate each other or love each other (50% chance of each).