Tasha's Cauldron of Everything is a sourcebook for the 5th edition of the Dungeons & Dragons fantasy role-playing game, published in 2020. The book is a supplement to the 5th edition Dungeon Master's Guide (2014) and Player's Handbook (2014).

The book adds a variety of options for both players and Dungeon Masters along with marginalia by the archmage Tasha.

Tasha's Cauldron of Everything was published on November 17, 2020 and features cover art by Magali Villeneuve. An alternate cover is available only in local game stores with art by Wylie Beckert. On the hidden elements within the alternate cover art, Beckert said, "My favorite thing to hide within the image was the spell Tasha’s hideous laughter. In the art brief, this was meant to be a scroll with identifying text on it. But I wanted to find a more subtle way to show it, hence the possessed scroll of laughing imps and skulls. The art brief also called for Graz’zt to be 'looking flirtatious'. I figured the flirtiest he could get would be offering Tasha a uniquely demonic valentine".

The book features "in-character commentary from Tasha", as well as several new spells and magic items iconic of the character. The book also includes a "de-Eberroned" version of the group patron mechanic and of the artificer class and its subclasses, along with reprints of several subclasses that were previously published in other supplements for specific campaign settings: the Order Domain Cleric and Circle of Spores Druid from Guildmasters’ Guide to Ravnica, College of Eloquence Bard and Oath of Glory Paladin from Mythic Odysseys of Theros, and the Bladesinging Wizard from Sword Coast Adventurer’s Guide.

In August 2020, it was widely reported that the book would include "a new way to create characters that’s fully customizable and in line with the game’s push for diversity and representation". Jeremy Crawford said that the options would "better reflect the story you have in mind for the characters". Much of the information in Tasha’s Cauldron of Everything was developed through the public Unearthed Arcana playtest – of the playtest subclasses, Crawford said "almost every single one made it into the game".

In November 2020, Crawford contrasted the book's new optional character creation rules with the game's original racial ability score bonuses, saying "Contrary to what many people might think those ability score increases that are in those different options, they're not there for game balance purposes. They are there strictly to reinforce the different archetypes that have been in D&D going all the way back to the '70s. [...] It really has been just about archetype reinforcement, and because it's not there for game balance reasons we give people the option in Tasha's Cauldron to take whatever those bonuses are [...] put them in any ability score you want".

Dungeons & Dragons Rules Expansion Gift Set, a boxed set, contains Mordenkainen Presents: Monsters of the Multiverse (2022) along with new printings of Xanathar's Guide to Everything (2017) and Tasha's Cauldron of Everything; it was released on January 25, 2022. An exclusive edition, with white foil alternate art covers by Joy Ang, is only available through local game stores.

In August 2020, Corey Plante, for Inverse, wrote: "All things considered, Tasha’s Cauldron of Everything already feels like a must-buy as the most important D&D book of 2020 that players will be reference for many years to come". Scott Baird, for Screen Rant, highlighted the slow release schedule of 5th edition Dungeons & Dragons and that "Tasha's Cauldron of Everything might offer some of the biggest additions to the game since it was first launched".