The Seven Dwarfs are the well-known fairytale characters from the fairy tale "Snow White and the Seven Dwarfs", first appearing in the stories of the Brothers Grimm. When Snow White flees from the evil queen, the seven dwarfs take her into their home in the forest. When they find her after she has eaten from the poisoned apple and assume she is dead, they fashion a glass coffin for her.
The Land of Stories series takes place after the traditional fairy tale ends and Snow White has married her prince and rules as queen. It is mentioned that the Seven Dwarfs still live in the Dwarf Forests, but visit Queen Snow White at her palace occasionally. They are mentioned in The Wishing Spell, but first appear in The Enchantress Returns, ch 24.
Appearance and Personality
True to the traditional fairy tale, the dwarfs are miners. Three of them are described simply as "The Oldest", "The Largest" and "The Shortest". 
It is revealed that there was in fact an eighth dwarf: Rumplestiltskin. He is their brother, but turned away from the mines a long time ago. When he visits them to warn them for the Enchantress, they turn him out, rejecting him as family because of the things he did while working for Ezmia.
After Rumplestiltskin sacrifices his life for Alex and the Land of Stories, the seven dwarfs are very sad and arrange his funeral in loving detail, making a bejeweled coffin for him just as they had for Snow White, and placing it in one of Rumplestiltskin's favourite spots in the forest.
"You abandoned this family a long time ago when you decided we weren't good enough for you. And what did you leave us for? To kidnap children for evil fairies? To spend a lifetime in prison? How dare you call yourself a dwarf or say the word family under this roof! Mother and Father would be ashamed if they were still alive."