Rumplestilskin aka Mr. Gold
Before the Curse:Rumplestilskin, has lived a life of torture. His father abandoned him as a child, and later his wife left him for a pirate because she thought he was a coward. Not only that, but she left their son, Baelfire, with him. Rumple struggles to be a good father, and to protect his boy he becomes the "Dark One", but with this new magic comes a price. He becomes power driven without realizing it, and loses his son because of the very thing he thought would keep them together. When he loses his son he becomes angry, he hurts other people because he no longer feels anything but pain himself... Until he meets Belle.
After the Curse:Since Rumple was the "Dark One" he was a force to be reckoned with, even to Regina the "Evil Queen". He made it so he still had his memory after the curse that Regina cast.
In Storybrooke he is known as Mr. Gold, a pawn salesman who who holds a lot of power in the community. Everyone in town is scared of him except the town mayor, Regina. Mr. Gold is still out for just plain old revenge because he believes Belle to be dead, but on top of that, he has a plan that could bring magic to Storybrooke. But is that a good or bad thing?