All Diablo 4 Unique items and how to get them

This is the most powerful gear in Diablo 4, including the seven ultra rare "Uber Uniques."

Each of the Diablo 4 Unique items are powerful piece of gear you can get in the game, enhancing your class abilities, or providing strong secondary effects. But with great power comes a greatly decreased drop rate. It's fairly rare to wrangle one of these before reaching the endgame. And it's even more rare to find one of the eight "Uber Unique" items.
The only guaranteed way to get a Unique item is to beat Blizzard's par time in The Gauntlet, a weekly dungeon with a time limit and leaderboards. If you are fast enough to earn the Seal of the Worthy (which isn't hard at level 100), the cache you receive the following week will have a 100% chance to include a Unique item.
Otherwise, Uniques can be found by opening Helltide chests, completing Nightmare Dungeons and tiers of The Pit, or by summoning endgame bosses to target farm them. Either way, here's every Diablo 4 Unique item, plus the best ways I've found of farming them in the game. If any more show up, I'll be sure to add them to the list—most recently, I added the new Unique items for the fourth season, plus info about targeting farming Unique items with endgame bosses.

HOW TO GET UNIQUE ITEMS

Unique items drop as potential loot in all world tiers. You can get them from anything in the game, like Tree of Whispers caches, World Bosses, Helltide chests, Nightmare Dungeons, and The Pit. Your best chance at seeing one will largely depend on the speed at which you can complete a particular activity, which means for most people it'll be Nightmare Dungeons.

HOW TO GET UBER UNIQUE ITEMS

Although they're still classified as Unique items, Diablo 4 has eight "Uber Unique" items with a very low drop rate (estimated to be around 2% as of season 3). Each of these drop at item power 925, and are the only items in the game with fixed stats (there's no range of different rolls you can get). Uber Uniques have extremely powerful stats on them and equally powerful special effects, like the Harlequin Crest's bonus ranks to all your active skills.

Uber Uniques drop from level 55 monsters or higher, which means your best chance at seeing one is in world tier 3 or 4.

Nightmare Dungeons can drop Uber Uniques as early as tier 2, but the best way to target-farm them is by defeating the two endgame bosses with the highest drop chance: Echo of Duriel or Echo of Andariel. Additionally, the level 200 Tormented versions of both bosses will have an even higher chance of dropping Uber Uniques.

Uber Uniques can be salvaged at a blacksmith to receive a Resplendent Spark. Once you have four Resplendent Sparks, you can visit an Alchemist to craft one Uber Unique of your choice. Resplendent Sparks are also available from other sources, like defeating Uber Lilith and your first level 200 Tormented Echo boss.