Unearthed Arcana (abbreviated UA)^[1] is the title shared by two hardback books published for different editions of the Dungeons & Dragons fantasy role-playing game. Both were designed as supplements to the core rulebooks, containing material that expanded upon other rules.

The original Unearthed Arcana was written primarily by Gary Gygax, and published by game publisher TSR in 1985 for use with the Advanced Dungeons & Dragons first edition rules. The book consisted mostly of material previously published in magazines, and included new races, classes, and other material to expand the rules in the Dungeon Masters Guide and Players Handbook. The book was notorious for its considerable number of errors, and was received negatively by the gaming press whose criticisms targeted the over-powered races and classes, among other issues. Gygax intended to use the book's content for a planned second edition of Advanced Dungeons & Dragons; however, much of the book's content was not reused in the second edition, which went into development shortly after Gygax's departure from TSR.

A second book titled Unearthed Arcana was produced by Wizards of the Coast for Dungeons & Dragons third edition in 2004. The designers did not reproduce material from the original book, but instead attempted to emulate its purpose by providing variant rules and options to change the game itself.

The title Unearthed Arcana is also used for a regular series on the official Dungeons & Dragons website that presents new playtest content for Dungeons & Dragons fifth edition.

The second book to use the name Unearthed Arcana was written by Andy Collins, Jesse Decker, David Noonan, and Rich Redman, and published in February 2004 by Wizards of the Coast, for use with the Dungeons & Dragons third edition rules.^[22] Cover art was by Matt Cavotta, with interior art by Steven Belledin, Ed Cox, Wayne England, Emily Fiegenschuh, David Hudnut, Jeremy Jarvis, Doug Kovacs, John and Laura Lakey, David Martin, Dennis Crabapple McClain, Mark Nelson, James Pavelec, Steve Prescott, David Roach, Richard Sardinha, Ron Spencer, Stephen Tappin, Joel Thomas, and Ben Thompson.^[22]

The designers intended the book for experienced players and Dungeons Masters who wanted something new, encouraging them to customize the game's rules. The designers did not want the third edition book to be like the original Unearthed Arcana mechanically, because according to Andy Collins: "Every book on the market looks like the original Unearthed Arcana. New classes, new spells, new magic items - that's the default "recipe" for a d20 product these days. We saw no need to do that with this book."^[23] Where the original Unearthed Arcana had simply expanded the rules and options of the core game, this 224-page supplement was aimed at providing an extensive list of variant rules and options to change the standard game itself.^[23] The volume of options added was intentionally excessive; according to the designers, a Dungeon Master who reads the book must be prepared to "Drink from the fire hose"^[22]: 4 and to think before using options that may radically imbalance the game.^[23] The book ends with a checklist of the included variants, preceded by a short chapter discussing ways of transitioning among multiple games using different rulesets (one of which explicitly emulates the "Eternal Champion" stories of Michael Moorcock).

The Unearthed Arcana title has been used for a semi-regular series of digital releases at the official D&D website that began in February 2015; the series presents new, work-in-progress content such as class archetypes, playable races, and rule variants, similar to the playtest process that preceded the release of 5th edition.^[24][25][26] Much of the information in Xanathar's Guide to Everything (2017)^[25] and Tasha's Cauldron of Everything (2020) was developed through the public Unearthed Arcana playtest.^[27] On the playtest subclasses developed for Tasha’s Cauldron of Everything, Jeremy Crawford said "almost every single one made it into the game".^[27] Starting in January 2018, Unearthed Arcana content was generally added to D&D Beyond approximately one week after it was released on the official D&D website.^[28][29] Once the playtest period has concluded for Unearthed Arcana content (whether it is published in a book or retired, as determined by Wizards of the Coast), it is archived on D&D Beyond; existing character sheets already using the content are able to continue doing so, but the archived playtest content can not be newly added to a character.^[28]

Since August 2022^[update], Unearthed Arcana articles have featured One D&D playtest material with releases now exclusive to D&D Beyond.^[30][31][32] In August 2023, Crawford stated that since originally launching Unearthed Arcana they have "received more than 500,000 surveys from players based on their time spent with the" playtest content.^[33]

Reaction to the Unearthed Arcana hardcover was often critical. According to Lawrence Schick, in his 1991 book Heroic Worlds, "Many players regard the new character classes introduced in this volume as overly powerful and out of line with those in the Player's Handbook."^[14]

Paul Cockburn reviewed the original Unearthed Arcana in issue 73 of White Dwarf magazine (January 1986), rating it 4 out of 10 overall. He summed up the book's contents by calling them "A rules extension package of reprints, most of which add very little of interest or value to anybody's game."^[5]

William B. Haddon's review of the third edition Unearthed Arcana on RPGnet lauded the book's content while criticizing the interest level of the content as "very flat". He found the power level unbalanced for each of the new sub-systems introduced, and found little in the suggested rules that he wanted to use.^[152]

Viktor Coble listed Unearthed Arcana as #10 on CBR's 2021 "D&D: 10 Best Supplemental Handbooks" list, stating that "If there is ever a supplemental guide to include in a player's library, it's any of the "Unearthed Arcana" editions. They're by far one of the most useful handbooks D&D ever puts out, and are rarely a regretted addition."^[153]

James Maliszewski for Black Gate in 2014 said "Unearthed Arcana was a game changer by being something I didn't want. Or perhaps I should say that it simply failed to be what I hoped it would be. Even now, I'm not entirely sure what it was that I hoped the book would be. I know only that I once loved D&D without ceasing and, by the time, Unearthed Arcana came out, I no longer did. It would take years before I loved it again with the same passion I did in those heady early days. It's unfair to lay the blame for that on Unearthed Arcana, even though I did for years afterwards."^[154]

Scott Taylor of Black Gate listed the Unearthed Arcana as #3 on the list of "Top 10 'Orange Spine' AD&D Hardcovers By Jeff Easley, saying "Truly one of the most iconic wizard images EVER! How many times has this been ripped off?"^[155]