NASH: the language of the Old Ones (Nasenna). It is used by some human sorcerers as well, who have sought out ancient Chaotic magic. Since Orcs were first created/summoned by the Old Ones, most orcs speak a simplified version of Nash.
TROLLISH: this language (with no written form) is spoken by Ogres, Trolls, Gnolls and most sorts of Giants.
SHISHARN: the ancient language of the Serpent-Men of antiquity. Some sorcerers learn it to research and cast spells and rituals. The modern languages of Lizardmen, Troglodytes and Kobolds are all just simplified, spoken forms of Shisharn.