Alice in Wonderland

One of the foundational works of modern fantasy, Alice's Adventures in Wonderland and Through the Looking-Glass, and What Alice Found There were written by Charles Lutwidge Dodgson (pen name: Lewis Caroll) in 1865 and 1871, and have been a source of stock shoutouts in RPGs for a very long time.

One of the first full cases of Isekai and the "All Just A Dream" ending, but because both were rare at the time, it gets a pass for both.

A favorite mining spot for RPGs in a hurry for new content, Wonderland's monsters and creatures are very much a stock reference.

Here are a few common items to get the nod in /tg/-related stuff:

• The Jabberwocky: A dragon of some kind.
• The Jubjub bird: From the same poem as the above.
• A Vorpal Blade: From the poem about the Jabberwocky. If you see one of these, it's descended from a nod to Caroll (who invented the word "Vorpal"), but after so many washings through the "designer in a hurry" machine, it's probable that that reference is forgotten.
• Snarks: Again, word made up by Caroll, in a semi-related work that gets a lot of shout-outs on its own, The Hunting of the Snark. If the referrer is clever, they'll make the Snark in question a "Boojum", which is much more dangerous.

Among notable /tg/-related shoutouts:

• Monster Girl Encyclopedia has just about all of 'em, in a special "Wonderland" made by an "Alice". Like we said, stock reference plus public domain = of course it's a thing he'd rip-off.
• "Dungeonland" and "The Land Beyond The Magic Mirror", a pair of notorious early Dungeons and Dragons adventure module written by Gary Gygax based more or less directly on the Duology.
• Just about all the creatures mentioned in the Jabberwocky poem have had a Dungeons & Dragons monster made for them at some point. Some have had it been done to them several times.
• JAGS Wonderland, a psychedelic horror RPG very loosely based on the Wonderland setting. Has a reputation for being an interesting setting stuck to a mediocre system.