Items - Whyte, the wolf healer. (Will increase what you can craft if you increase your relationship with him.)
Specialty Items - Victory, the fox dancer.
Weapons - Hammer, the tiger blacksmith. (Will increase what you can craft if you increase your relationship with him.)
Armor/Accessories - Felix, the feline dressmaker. (Will increase what you can craft if you increase your relationship with him.)
Elemental Items - Sen, the goat vintner - you will need to take a chaos seed or blood of chaos before long, otherwise you will get a bad ending.
Merchant - Nibbles, the rat pub owner - he is the only way you can sell items in the game.