Prompt Generators

Anthropomorphic - Characters are arguably conscious inanimate objects.
Ballroom Dance Lessons - Character needs to learn how to ballroom dance for some formal event, love interest character helps them. Mostly fodder for the physical intimacy that is ballroom dancing. Usually ends in character asking love interest to the formal event as a date, but not always, in which case it's good jealousy fodder.
Bond - Also known as soulbond, it comes with the main trait of two characters are "bonded" together in a way that affects their physical lifestyle. Oftentimes it manifests as a physical distance bond, where physical distance between two characters cause immense pain (particularly headaches) while more intimate physical interaction quells it or produces a pleasant feeling. Other times, this may be accompanied by telepathic communication or detecting/adapting each other's emotions. Alternatively, telepathy/empathy may be the main trait of the bond, without any physical distance/pain.
Canon Divergence - The fanwork is canon up to a point, until an area of the canon's narrative is decidedly changed by the fan creator. The resulting work thus diverges from canon.
Catboy/Kemonomimi - Listed catboy as well since it tends to be more popular, but mostly just humans with beast ears and sometimes also the respective beast's tail.
Character Death Fix - Is a character dead in canon? Well, not anymore! (does not necessarily have to explore narrative differences but tends to go in that direction.)
Comedy of Errors - See Identity Porn
Crossover Fusion - A crossover that occurs between characters of one fandom, and the setting and/or plot of another fandom. For example, Naruto characters simply in the Harry Potter world, and a Pokémon fic that not only takes place in but also echoes the plotline of Harry Potter, are both considered crossover fusions.
Daily Prophet Ad - As opposed to a Craigslist ad.
Denialfic - Something happen in canon that you really, really wish it didn't? Well. It didn't happen in your denialfic/fanwork.
Dominance Hierarchy - Similar in structure to Omegaverse, that everyone is born with an additional "gender"/role that plays a part in the overall social-genetic hierarchy, ex. D/s universe (everyone is born as a Dom, Sub, or Switch), Sentinel AU (everyone is born as either a Sentinel or a Guide), or whatever you can come up with.
Doppelgangers vs Twin AU

Doppelgangers largely refers to fanwork where a) a character's personality is split into two doppelgangers, each representing that personality half of a character b) a stranger appears and happens to look similar to the main canon character (or, but less common, c) cloning is involved.) The "stranger" usually has some foundation, such as Marcel in One Direction's Best Song Ever, or a kpop artist's Chinese or English names, or a same-actor crossover.
Twin AU is an AU where a character has always had a twin all along. The twin often takes the canonical narrative position of the character in question, while the character we know embarks on a different life. For example, a Panic! at the Disco one, and the better known Lightning on the Wave's Sacrifices Arc (Harry Potter.)

Drabble Collection - Collections of 100-word scenes/summaries of events, often told as separate vignettes tied into one cohesive story.
Fairy Tale AU - Follows the narrative beats and general premise of a fairy tale, but does not necessarily have to imitate the setting or fantastical rules. For example, there are at least four modern day movies that have "Cinderella Story" in the title but don't have actual princes or fairy godmothers. Can exist in canon; does not necessarily have to be "AU," such as a Draco/Harry werewolf story based on Beauty & the Beast but takes place in its canon world.
Femslash/slash AU - My way of saying genderswap (note: not necessarily "sexswap") and still/now gay
Fever Dream - Due to a sickness, drugs, or any other form of inebriation, the character experiences 'visions' that later may be revealed to be a glimpse into the future, premonitions, uncover a character's hidden emotions for another (these are usually somewhat intimate or sexual in nature), or other mystical half-conscious symbols.
Five Things/Times - See 5+1 vs Five Things/Times
Fix-It - Something happen in your canon that you didn't like? That upset you? That's just kinda dumb? If you're writing a fic where that doesn't happen, where unresolved issues get resolved and bad characterizations get redeemed and everyone gets a happy ending, then you're writing a fix-it fic.
Flangst - fluff & angst
Forced Obedience/Mind Control - Think Ella Enchanted
Genderfuck/Sexswap - Character wakes up with not-assigned-at-birth body parts. Usually either get-together fodder or porn fodder. Or both! Or character's body semi-regularly changes genitalia a la Ranma 1/2.
HDM Daemon AU - Animals representing the physical manifestation of a human's "inner soul"/personality, behave independently, can communicate with their human telepathically. Canonically invisible to most humans (visible to other daemons), but may hold exceptions in fic. Generally the 'opposite' sex as their human, and doesn't stay in a fixed form until the human has matured/in late teens/adulthood. I haven't read HDM, so the Fanlore page probably explains it better and more in-depth.
Heat/Mating Cycle - See Sex Pollen vs Heat/Mating Cycle
Identity Porn/Comedy of Errors - a la You've Got Mail, two characters know each other in two separate forms of communication and don't know that they're the same person until BIG REVEAL. Oftentimes characters dislike each other in one medium and get along in another; or ask for virtual dating advice for the person they know IRL and the person they know IRL happens to be on that forum and gives it to them.
In Vino Veritas - Under the influence of drugs, alcohol, magic, truth serum/potion/spell, fever, or otherwise inexplicable reason, a character reveals their love/lust for another.
Kemonomimi - See Catboy
Let Me Be Weak, Let Me Sleep - In ship fic, where one character dreams constantly of another, usually devolving into sexually explicit territory. As a direct result of the dreams' intensity (sexual or otherwise), the character usually suffers from insomnia and their personal/professional life tends to take a toll
Magic Hybrid Accident - Accident as a result of two (or more) elements of magic with different intents colliding, such as magical potion + magic plant, magical potion + spell, or two spells.
Mating Cycles/Heat - See Sex Pollen vs Heat/Mating Cycle
Mind Control - See Forced Obedience
Mirror Universe vs Role Reversal

Role Reversal would explore how the narrative would change if two (or more) characters had different roles
Mirrorverse tends to lift the entire story itself and present most things (at the author's discretion) opposite to canon, whether it be character roles, overall tone, character moral inclinations/behavior, the primary conflict, any relationships/character dynamics, and possibly the setting.

Mythology AU - Characters reimagined as mythological figures. More often than not fanart; in fic, mythological figures (such as Zeus and Poseidon) are recast as characters, or they follow the rules of the fairytale AU, where the fic follows similar premise/narrative beats of a myth but is not mythological in genre (ex. Hades/Persephone, Eurydice/Orpheus, Icarus.)
Non-volleyball AU - May apply to all characters or any one (or more) in particular
Order of the Phoenix - Deals directly with the organization/group that is the Order and its goals, as opposed to the fifth Harry Potter book.
Recursive Fic - Fanfiction/fanwork of a fanfiction/fanwork.
Role Reversal - See Mirrorverse vs Role Reversal
Sex Pollen vs Heat/Mating Cycles are very similar in overall ending result, but:

Sex Pollen often ends up inexplicable or more ambiguously explained. Also it does not have to be non-con as Fanlore says, just FYI. Take an example.
Heat/Mating Cycles has a character whose increased libido is caused solely by the character's biological instinct to mate; the character is usually part animal in some way. The character may have more specific needs when engaging in intercourse, such as knotting.

Sex Robot - Chobits; love interest character is a robot designed for sexual pleasure but oh no the human's feelings get involved!
Teamswap - One (or more) character canonically on one team is now in another, ex. Hinata in Seijou.
Twin AU - See Doppelganger vs Twin AU
Ulzzang - Someone who's popular on the internet only because they're attractive/their selfies are good. Korean term, but y'all probably know what thirst following is, so.
Universe Alteration - As opposed to canon divergence or alternate universe, the fic's universe is largely the same, except for one or a few exceptions. Some examples: a character's age, soulmate AUs in canon-verse, characters canonically not in a relationship are now in an established one (or vice versa). Some of these examples already exist as prompts, but this general one is for you to explore the possibilities as well.
Win/Loss AU - AU where a team that canonically won/lost a game now lost/won it.
5+1 vs Five Things/Times

5+1 is often something like "Five Times Dean Told Cas No, and One Time He Said Yes." (I just made this up I don't watch Supernatural.) (ok I've watched one season)
Five Things/Times is more like "Five Places Harry and Ron Kissed." They have different connotations, imo.

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