There are many tables for Dungeons and Dragons Encounters here, many adapted from my Encounters on DM's Guild.
The categories here are the Common & Uncommon Terrains, Collected Encounters, Noncombat Encounters and Spelljammer Encounters.
There is a list of all the most recent D&D Encounters articles.
The 11 Common Terrains and More Unusual Ones
The basic 11 D&D terrains are the ones used by the 5E Dungeon Master's Guide and Monster Manual, each with encounters, hazards, npcs and more.
arctic | coastal | desert | forest | grassland | hill | jungle | mountain | swamp | underdark | underwater | urban
Then there are several more "unusual" terrains.
Unusual terrains - feywild | shadowfell | lower planes | elemental | jungle | roads | ruins | sea
Collected Encounters Tables
There are also tables taken from the Collected Encounters list
Terrains of caves | dungeon | farmland | market | river | sewers | sky
Creatures of demons | devils | goblinoids | restless spirits | undead
Many of the encounters are Noncombat Encounters, including
Basic Tables - wilds & ruins | underground | travelers | city & village | level 1-10 | level 11+ | orcs
City and Undercity Noncombat tables - city streets | rich & poor | docks | vendors & guards | taverns & parks | back streets | fences & intrigue | shady | sewers | ruins
Non-combat by terrain - arctic | coastal | desert | forest | grassland | hill | mountain | swamp | underdark | underwater | urban
Non-combat by unusual terrain - feywild | jungle | road | ruins | sea | shadowfell
Spelljammer is well represented with regular encounter tables and Non-Combat ones.
Encounters - astral sea | asteroids | dead gods | rock of bral | wildspace | ships |
Spelljammer noncombat - wildspace & asteroids | astral & dead gods | bral & merchants | ships & captains | events & anomalies
As well as Alliterative Adversaries! - A-E | F-J | K-O | P-T | U-Z
Last are simple tables by letter to get results such Mesmerizing Mimics, Zany Zombies or a Blinded Beholder.
D&D Alliterative Adversaries - A-E | F-J | K-O | P-T | U-Z