There are 27 kinds of creatures in Dungeon Master, and many creature generators triggered by walking in the dungeon.
The Dungeon Master Creatures names on this site are those found on page 12 of the Hint Book - Dungeon Master Adventurer's Handbook, which is the official Dungeon Master hint book. The internal names are also the same (they can be found inside the graphics.dat file of both Dungeon Master for PC version 3.4 Multilingual and Dungeon Master for Amiga version 3.6).
You will find all the characteristics and abilities of creatures on Technical Documentation - Dungeon Master and Chaos Strikes Back Creature Details.
Fighting tips:

Groups: 1-4
Spells: None
Item(s) dropped when killed: None
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: None
Item(s) dropped when killed: Screamer Slice (1-2)
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: None
Item(s) dropped when killed: Rock (0-2), Boulder (1-2)
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: None
Item(s) dropped when killed: Club
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-2
Spells: None
Item(s) dropped when killed: Worm Round (1-3)
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: None
Item(s) dropped when killed: None
Sounds:
Movement sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: None
Item(s) dropped when killed: None
Sounds:
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: Slime
Item(s) dropped when killed: None
Sounds:
Movement sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1
Spells: None
Item(s) dropped when killed: None
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: Lightning Bolt, Open Door
Item(s) dropped when killed: None
Sounds: None
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: None
Item(s) dropped when killed: Wooden Shield, Falchion
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1
Spells: None
Item(s) dropped when killed: Stone Club
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: None
Item(s) dropped when killed: None
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)
Note: Can steal items in champions' hands

Groups: 1-2
Spells: None
Item(s) dropped when killed: Drumstick (1-2)
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: Open Door, Poison Cloud, Fireball, Lightning Bolt
Item(s) dropped when killed: None
Sounds:
Movement sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-2
Spells: None
Item(s) dropped when killed: None
Sounds:
Movement sound
Location(s) (Level, X, Y)(Number of Creatures)
Note: Rusters were supposed to 'rust' your weapons but this was never programmed.

Groups: 1
Spells: None
Item(s) dropped when killed: None
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1
Spells: None
Item(s) dropped when killed: None
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: None
Item(s) dropped when killed: Armet, Torso Plate, Leg Plate, Foot Plate, Sword (2)
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1
Spells: None
Item(s) dropped when killed: None
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1-4
Spells: Poison Cloud, Fireball
Item(s) dropped when killed: None
Sounds: None
Location(s) (Level, X, Y)(Number of Creatures)
Note: A 'Weaken Nonmaterial Beings' spell will pass through a Materializer when it is not in a materialized state. However, you can still kill them whith this spell when they are not materialized if there is a wall behind them on which the spell will explode and cause damage to the creature. The 'Disrupt' attack of the Vorpal Blade always works on a Materializer even if it is not in a materialized state.

Groups: 1
Spells: None
Item(s) dropped when killed: None
Sounds: None
Location(s) (Level, X, Y)(Number of Creatures)
Note: Black Flames absorb fireballs and turn them into health (up to a maximum of 1000 hit points).

Groups: 1-4
Spells: Fireball
Item(s) dropped when killed: None
Sounds:
Movement sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1
Spells: Fireball
Item(s) dropped when killed: Dragon Steak (8-10)
Sounds:
Movement sound
Attack sound
Location(s) (Level, X, Y)(Number of Creatures)

Groups: 1
Spells: Fireball, Lightning Bolt, Poison Cloud, Open Door
Item(s) dropped when killed: None
Sounds: None
Location(s) (Level, X, Y)(Number of Creatures)
Note: Lord Chaos can teleport up to 2 tiles away, including across walls and closed doors. He does not take any damage.

Sounds: None
Location(s) (Level, X, Y)(Number of Creatures)
Note: Lord Order appears when The Firestaff is used to fuse Lord Chaos with him at the end of the game. You will also encounter him if you go back to the entrance of the dungeon with the Firestaff (without the power gem). See Dungeon Master Level 00.

Sounds: None
Location(s) (Level, X, Y)(Number of Creatures)
Note: The Grey Lord briefly appears after the fusion of Lord Chaos and Lord Order, at the end of the game.