The missing dwarf is Happy! Shown are Sneezy, Sleepy, Bashful, Grumpy, Dopey and Doc. They are a group of seven dwarfs from the fairy tale "Snow White", and from the 1937 Disney movie "Snow White and the Seven Dwarfs".

In the movie the seven dwarfs live in a tiny cottage and work in the nearby mines. Snow White happened upon their house while fleeing from the wicked Queen's kingdom. The Seven Dwarfs returned home and immediately noticed someone had sneaked in, because the house was cleaned. She awakens and explained her situation. They agree to let her clean house for them but they warn her to be careful when alone at home, and to not let anyone in while they are in the mountains.

The Queen disguised as an old peddler ties a colorful, silky bodice on Snow White which causes her to faint. the Seven Dwarfs return just in time to revive her. The Queen dresses as a comb seller and gives Snow White a poisoned comb, the Seven Dwarfs save her again. The Queen then appears disguised as a farmer's wife and gives Snow White a poisoned apple, of which she takes a bite. This time, the Seven Dwarfs are unable to revive her. Assuming she is dead, they place her in a glass coffin.

A Prince sees Snow White. Enchanted by her beauty, he falls in love with her. The Dwarfs let him take the coffin, and as his servants carry the coffin, they stumble and the piece of apple comes out of Snow White's throat, reviving her. Love unites them and they live "happily ever after"!

More Info: en.wikipedia.org