Intelligent humanoids of the ‘dark

From a Dwarven perspective:

A Drow male
  • The Drow are the most famous of the underdark denizens that live at a similar depth. They are instantly hostile, but rarely encountered: zones of control of each race is deliberately avoided by the other. They speak Drow Elven and Undercommon.
  • Troglodytes eat Dwarves, and almost anything else. They are the Tasmanian Devils of the ‘dark. They speak Troglodyte and sometimes Undercommon.
A Goblin on a clockwork mount
  • Goblins once lived in the ‘dark but have migrated up to serve powerful surfaces creatures. Some tribes still live below the earth and may occasionally hunt into the underdark proper. Dwarves and Goblins do not get along: a longstanding racial hatred is mutual between both cultures. Goblins are at least as industrious and, in some ways, as technologically advanced as Dwarves. Goblins speak Goblinoid.
  • Grimlocks are tribal denizens that live below Dwarven reaches. Their society is unknown to the surface dwellers but can be appreciated by underdark denizens (including Dwarves). They create amazing music and poetry (all Grimlocks are blind) which can sometimes be heard far away from their nests. Their primary predator are the illithids, they are neutral toward Dwarves. Grimlocks speak Undercommon.
Kuo-toa mage
  • Kuo Toas or fish-frog-men are another intelligent humanoid species that ally with the Drow and eat Dwarves. They dwell below Dwarven areas and experience has found them to be extremely chaotic: casting magic missle willy-nilly and erotically embracing undead overlords. They are hostile almost without exception and speak Kuo-Toan, Aquan and Undercommon.
  • Illithids dwell well below the Dwarves and are rarely allowed into even the international zone – though the odd exception has been made, with massive precautions. They speak Illithid and Undercommon.
Derro - the mutated, murderous member of the Dwarf species
  • Derro are mutated, homicidal Dwarves that are declared Khazad Non Grata, allowing Dwarves to kill them on sight despite Derro being technically Dwarfkind. Derro speak Dwarf and Undercommon.
  • Svirfneblin are incredibly elusive subterran gnomes. They are non-hostile toward Dwarves, though suspicious and cautious of encounters with all folk. They speak Gnome and Undercommon.