Chapter Summary

▼ Potter Canon: How this guide uses the term "canon," resources for finding canonical information, and a few deep dive analyses of canon that others have written.
▼ Potter Fanon: General worldbuilding and other resources which set themselves in the HP universe but aren't canonical. This includes maps, theorizing on the locations of different things, etc.
▼ IRL: Useful stuff that isn't tied to the Harry Potter universe, like old maps, an 1828 dictionary, and several databases of edible plants, mushrooms, and etc. in Scotland.
▼ Changelog: It's a changelog.
Click the arrows (▼ and ▲) in order to quickly navigate between sections.

Potter Canon ▲

Defining Canon

Practically every reader takes the seven Harry Potter-titled books, PS to DH, as canon. Most will also take the books Fantastic Beasts and Where to Find Them and Quidditch Through the Ages as canon. Plenty of people use the films and even the video games to supplement this, but if your fic gives priority to the films over the books then you're best off mentioning this at the beginning so that nobody has the wrong expectations. A significant minority of writers and readers ignore the Fantastic Beasts movies, in whole or in part, and you shouldn't feel weird about doing the same (though, again, it might be good to telegraph that fact in some way before it becomes a plot-crucial point).

If I say that something is "canon" or "canonical," without specifying further, then I'm probably talking about "Book+" Canon: The seven main books plus Fantastic Beasts and Quidditch.

General Resources

I figure that anyone who's reading this already knows about the Harry Potter Wiki, but if you didn't, now you do. Be warned that HPW is a mess, though. It insists on treating everything as canonical unless it specifically contradicts the books, which means that the Wiki's vision of canon exists in a weird superposition where Death Eaters collapsed both the Brockdale Bridge and the Millennium Bridge, even though construction on the latter didn't even begin until 1998: “Fudge refused to step down, and thus Voldemort ordered Death Eaters to cause the Brockdale Bridge and the Millennium Bridge to collapse.”

Despite its penchant for treating LEGO Harry Potter as canonical, the Harry Potter Wiki is (like the real Wikipedia) still a decent starting point if you aren't sure about something. In particular, its page on the 1991-1992 school year has a list of every canonical professor and student attending Hogwarts at that time, with students organized by year.

Other general resources:

• The Harry Potter Lexicon has much less information than HPW, but is far, far better sourced.
• In "Crazily Comprehensive Canon Exploration of Goblins," Choice Caterpillar checks every canonical reference to goblins and gives a thorough analysis of what the books tell us about goblins. Backup here.
• White Hound's "Sectumsempra and the nature of curses" makes an argument for the workings of Sectumsempra. Whether or not you agree, it's probably good for a refresher on what canon does and doesn't say about Sectumsempra and curses in general.
• Potter Search allows you to search the text of all seven books.
• Accio Quote collects a trove of quotes and comments by J. K. Rowling.

Timelines

• Harry Potter Lexicon's Timeline of events in the life of Voldemort | Tom Riddle, Jr. is particularly useful.
• The Hogwarts Years: Classmates, Birthdays, and Ages, compiled by smallbrownfrog, has information not only for the period of the seven books but also clarifies who was, or might have been, present at the same time as James and Lily, Arthur and Molly, Tom Riddle, etc.
• White Hound wrote a comprehensive list of “Birthdates in the Harry Potter universe.” Sorry, did I say “list?” I meant “essay.” 20,000 words.

List(s) of Terms Served

Because I find myself checking things like this fairly frequently, and consulting the Reference Guide is more convenient for me than dealing with the Fandom.com wiki, I'm stashing a couple of quick timelines here.

Potter Fanon ▲

General Resources

• The Monster Blog of Monsters has beasts, beings, diseases (e.g. lingua franca), spirits (e.g. animal ghosts), magical substances and objects (e.g. goblin ironwork), strange phenomena (e.g. filmic dissipation), excerpts from fake articles, and more. Much of it fails to fit the flavor of my personal canon(s), but it's still a goldmine.
• You may want to skim White Hound's “Fanon versus canon” essay. A lot of it is about Snape, but there are also sections like “Dumbledore habitually offers people sherbet lemons,” “The dungeons of Hogwarts are cold,” and “James and Sirius were Aurors.”
• Taure's “Canon Plus” document gives an overview of his version of canon, and touches on everything from the Gamp's Law of Elemental Transfiguration (and its exceptions) to the number of Galleons in Harry Potter's vault.
• Taure has also written on a "Small Wizarding World," which "depicts a version of the wizarding world which is more integrated with the Muggle world as a sub-culture rather than a fully independent society."
• If you're writing any kind of reinterpretation of the series, whether canon-compliant or fully AU, then you may be interested in reading the Ultimate Unofficial Guide to the Mysteries of Harry Potter. The book is hopelessly obsolete as a canon resource, but the “mysteries,” and especially the chapter on “Book 5 and Beyond,” can help you to see the series (especially the first four books) with fresh eyes. Quirrell doesn't really have a place in most fanfics, but the Guide points out that Quirrell was only “left to die” by Voldemort; there's some interesting wiggle room there, if you want to seize it. Not all of this analysis is all that great, though. The Guide seems to think that most relevant thing about the myth of Romulus and Remus is that Remus was killed by his brother, and not, say, that Remus was raised by a wolf.

Locations

• White Hound's essay on Spinner's End: what canon tells us, where in England it (and Cokeworth) may be, and what the houses may look like (inc. floorplans).
• White Hound has written a number of essays on how certain locations may fit into the wider world, both historically and geographically. She's also written on Godric's Hollow, Ottery St. Catchpole, Shell Cottage & Tinworth, and Little Whinging, and an essay that handles Grimmauld Place, the Ministry, and St. Mungo's together. Go here for a few more essays. Her Other page discusses Upper Flagley, Great & Little Hangleton, Malfoy Manor, and the Forest of Dean.
• FirePhoenix86, fyhjp, and Notsalony have each drawn up floor plans for 12 Grimmauld Place.

Wands

• “Agata Gregorovich's Guide To Wandlore,” by Faithless_3105, has lists of wand woods and wand cores (including botanical and mineral cores), and briefly discusses wandstaining, wands made from non-wood substances, and schools of magic.
• “An Independent Wandmaker's Guide for the Magical World” is an incomplete AO3 mirror of the Wandmore tumblr.
• Wandmore discusses wand cores (e.g. hippogriff feather) and wand woods (e.g. coconut), wandlore (e.g. Polish wand woods and cores), wands for canon characters, and more.
• “The Wood Database” collects an incredible amount of information about an incredible number of woods: common names, scientific name, size of the tree, dry weight of the wood, hardness, appearance, odor, workability… If you want to say more about a wand's wood than just its magical properties, then make sure to consult this database.
• Wandmore: “Wand lore, wand theories, and theorising the possible nature and character of a wand's Master.”
• Witchcraft & Wizardry's page on Wandlore.

IRL ▲

General Resources

• “Classical Literature for Fandom Purposes,” by splendide_mendax, is an AO3 guide to Greek and Latin literature.
• Color of Art Pigment Database, with alternative names, chemical composition, and other facts (e.g. this or that pigment may be primarily used in inks) for each pigment.
• The Medieval Bestiary collects an incredible number of, uh, Medieval bestiaries. You can look at the manuscripts individually or read everything that is said about this or that beast.
• Old Book Illustrations, New Constellation Symbols, and Astronomical/Astrological symbols for other planets' moons, all in the public domain.
• FamilySearch's Cousin Calculator will let you determine the exact relationship between two distantly-related family members. For example, by cross-referencing the Black Family Tree, we can see that Draco and Ron are third cousins once removed, Scorpius and Albus (Potter) are fourth cousins once removed, and Sirius Black is his own third cousin.
• FamilySearch discusses occupations and other topics in great depth. Start with their page on the British Isles and progress in whatever direction makes the most sense: England, Ireland, Scotland, Wales, etc. For example, the Wales page has a map of that country's original historic counties, links to pages (with census information and other records) for each of those counties, a page on Welsh naming customs, another on taxation in Wales, etc. Besides these and similar pages, the single most useful resource may be the pages linked under “England Business and Occupations,” which you should peruse if you would like to know more about barkers, drovers, or postal workers.
• Riddles and more riddles: D100 of Tricks, Puzzles, and Riddles; Riddles for DMs.

British and Irish Stuff

Also check out "Plants, Animals, and Food," below.

• Biographical Index of English Drama Before 1660.
• Black and White and Read All Over: A Guide to British Newspapers.
• English Folk/Traditional Names for Common Plants & Herbs.
• Imperial Measures of Weight.
• UK climate averages.
• Aca Goldsmith wrote a timeline from 1926 to 1940, covering canonical events in Tom Riddle's life and the Second World War.
• Chronology of the Troubles, 1968 - 2002.

Language

Also check out "Names and Families," below.

• For old timey words, I recommend 1828 Webster's Dictionary. If your needs are even more archaic than that, then check out the Old English to Modern English Translator.
• Cornish Dictionary, exactly what it sounds like.
• Greek > Latin alphabet conversion, to turn Διογένης into Diogénēs, for example.
• If you're worried that a word might be too modern for wixes to use (or conversely, you feel that a word is too modern but aren't sure what to replace it with) then I recommend Wiktionary and the Online Etymology Dictionary.
• The Letters of Queen Victoria and How to Write Letters: A Manual of Correspondence are useful if you want to ape the style of Victorian letter-writing. The Victorian Art of Letterwriting is much more condensed.

Maps

• City Roads will render all of the roads in a specified city, with the ability to zoom in or out.
• Maps on the Web is a treasure trove: (11th century / Founding of Hogwarts) Commercial routes in Medieval Europe, Europe in 1000, North Sea Empire of Cnut the Great, Norman Conquest of England, Counties of England in 1086; (17th century / Statute of Secrecy) Iroquois Empire; Ottoman Empire, New Netherlands; (Other maps) England 924-39, Balkans in 1410, 1595 Map of Europe with rivers, Europe in 1700, Intelligibility between European languages.
• Old Maps Online is exactly what it sounds like. Useful for premodern eras, working out possible countries on the magical side of the Statute of Secrecy, etc.

Names and Families

• For the meanings of given names, I recommend starting at Behind the Name.
• For the meanings of surnames, I recommend starting at FamilySearch.org and following it up with the Internet Surname Database, which usually gives more information about family history than FamilySearch. For distribution, the best site is generally Geneanet, which allows you to refer only to records in a specific span of time from 1500 to 2023, and occasionally has information that isn't available on FamilySearch. If you're having trouble identifying a region that shows up on Geneanet, then cross-referencing the name on Ancestry will often help. If all else fails, you might be able to find track down a family on WikiTree, and Wikipedia is always a good last reference if you want to be really thorough. If you're lucky, you might even find additional resources to check. Wiktionary has also come in handy for me from time to time.
• For surnames related to places, Heritage Gateway and Survey of English Place-Names can help you out.
• Finally, don't discount Googling <name_here> "surname" and following whatever links look promising.
• Ship Names from 1480-01.

Plants, Animals, and Food

• Samantha Kelly's blog, Chasing London Street Food, and in particular her post, “The Evolution of Street Food,” is very useful if you want to spice up Diagon Alley and other wixen spaces with open-air fare.
• Guide to the farming calendar: a year in the life of a British farmer.
• Guide to seasonal foods (when to buy, harvest, plant, or sow)
• Scotland Food and Drink has a seasonality calendar for native fruits, herbs, seafood, vegetables, etc. You can also consult this other seasonality calendar on Visit Scotland, or this other, other seasonality calendar, which focuses on fruits and vegetables.
• Sowing timeline for vegetables.
• UK Farming Calendar
• Old-World Names for Herbs and Plants has a list of alternate names. The actual facticity of this page (indeed, anything on this website) is questionable, but it's at least good fodder for Wizarding terminology.
• Wild Food UK has a list of mushrooms and another list of plants, filterable by edibility and season.

Changelog ▲