Underarmor
Armor that goes under your players skin.
UndercastMod by skipperguy12, Genius_Fraser, GoldBattle, palechip, xIGBClutchIx, flv92, molenzwiebel
A custom made mod that tracks gameplay stats and has custom guis made for the oc.tc servers
Undercraft by ThePsionic
Minecraft meets Undertale
Underfell
This is still a demo but this is what I like to call the brother update
Underground Biomes by Exterminator Jeff, Grom PE
Adds underground biomes composed of layers of new rock types
Underground Biomes Ore Integration by Harley O'Connor
Extra ore integration for underground biomes.
Underground City Engineering by beanflame, GoldMain, Mr_zhao
Underground Ocean by Reoseah
Small mod that adds large caverns filled with water to world generation.
Underground_1_12_2 by Brick, MCreator
UnderlineFix by Axer
Fix the bug which has caused unable to type underline on OSX.
Underp Hangables by masa
Fixes the derpyness of the dropped items from Paintings and Item Frames when they are broken.