The OD&D Dwarves (and Gnomes)
they have a high level of magic resistance, and they thus add four levels when rolling saving throws (M&M p. 7)
they are the only characters able to fully employ the +3 Magic War Hammer (M&M p. 7)
they note slanting passages, traps, shifting walls and new construction in underground settings (M&M p. 7)
dwarves receive +1 in 6 chance to detect sound at doors (U&W p. 9)
they are able to speak the languages of Gnomes, Kobolds and
Goblins in addition to the usual tongues (M&M p. 7)
Because of their relatively small size, clumsy monsters like Ogres, Giants and the like will have a difficult time hitting Dwarves, so score only onehalf the usual hit points when a hit is scored (M&T p. 16). They same applies for Trolls (Chainmail p. 29)
Dwarves are about 62,5% the size of men (Chainmail p. 28)
Dwarves may operate in normal darkness as if it were light (Chainmail p. 29)
Disadvantage: When ordered by a "commander" or "leader" to attack goblins or kobolds, these will be attacked to the exclusion of orders to the contrary.
Dwarves move at: 9" / 6" / 3" (deduced from Chainmail p. 43)
Dwarves are aligned with LAW (Chainmail p. 39).