This is a wiki thread to collate some of the best random generators for D&D 5E.
Starting with a few I use.

Names
Many different D&D races at Fantasy Name Generators

Encounters
Tables from Xanathar's Guide to Monsters

NPCs
EN World's own NPC Generator from Sobran

Dungeons
Random Dungeon Generator from Donjon


Treasure
Hoards (and individuals) from Donjon