Where can I find some word lists?

Diceware lists (generally 7,776 words long)

The Electronic Frontier Foundation has published a few word lists for creating diceware passphrases.
- I'm pretty sure password manager BitWarden uses the EFF long list.
- KeePassXC uses the EFF long list with some minor modifications.
- Note: These lists often have a tab between the dice numbers and each word. Tidy can delete the dice numbers easily with something like tidy -D t -o clean_eff.txt eff_large_wordlist.txt or using the -i flag.
ulif's "diceware" seems to have collected a few word lists in its Github repo, along with a separate page that explains each of the lists.
dmuth's "diceware" program has a collection of lists (h/t atoponce)
Original "Reinhold" diceware list created by Arnold Reinhold. Though it has some issues.
- Arnold Reinhold hosts diceware lists in a variety of languages.

Bitcoin BIPS-0039 (2,048 words) (h/t atoponce)
Monero's word list (1,626 words) (h/t atoponce)
Mnemonicode is another word list optimized for pronunciation. I believe croc, a file transferring tool, uses it.
Magic Wormhole, a tool for transferring files, uses a version of the PGP Word List, which specifically tries to use pairs of words that are phonetically distinct.
Wagashi is a set of new, short word lists in English. They also offer emoji lists.
Session's English word list
simple1024 is a word list with 1024 common English words, an alternative to EFF's short word lists.

If you're using Linux or MacOS, you've likely got some long lists on your computer. Check /usr/share/dict/words or /usr/share/dict/american-english.
NSA's RandPassGenerator uses a massive 117,828-word list.
Niceware list (~65,000 words). I used Tidy to help create v 4.0.0 of this list!
Norvig Natural Language Corpus Data has a list of 333,000 commonly used words from the Google Web Trillion Word Corpus, as well as an assortment of other word lists.
British National Corpus (BNC) database and word frequency lists
Lists used by a program called webpassgen
SCOWL (Spell Checker Oriented Word Lists) and Friends is a database of information on English words useful for creating high-quality word lists suitable for use in spell checkers of most dialects of English."
- ENABLE2K seems to be an older version of the SCOWL project?

A collection of a few Public Domain Word Lists
A great list of word lists by Aaron Toponce.
A list of word lists.
Danish wordlists is a "collection of [Danish] wordlists for cracking danish passwords"
r/wordlists subreddit, which seems to have links to a few non-English word lists.
You can also scan GitHub's #wordlists topic
An XKCD-inspired passphrase generator with a collection of non-English word lists.

The EFF also has some fandom-inspired lists. They use a space between dice numbers and words, so Tidy can clean up with the -D s option. I prefer Aaron Toponce's proposed new fandom word lists.
I'm pretty sure this is 1Password's word list as of 2021.
- 1Password published a few slightly different word lists (one, two) in 2018.
SecureDrop has a few lists, including one of adjectives and one of nouns.
Jitsi has lists of nouns, verbs, adjectives, and adverbs for generating random room names.
A German word list that looks promising

I used Tidy to create Orchard Street Wordlists (as well as a few other word lists).