Storybrooke character: Mr. Gold
Fairytale Land character: Rumplestiltskin
Fairytale origin based on: Rumplestiltskin
Rumplestiltskin was originally a regular — and quite cowardly — man, who was tricked into killing the powerful Dark One, thereby transferring the Dark One's magic to himself. While he originally tried to use the powers for good, the curse corrupted him. His son, Baelfire, tried to save him by taking him through a portal to a "world without magic," but at the last second Rumplestiltskin was too afraid to go.
Losing Bae pushed Rumplestiltskin completely over the edge. He spent many years striking up deals, gathering power, and creating havoc in the Fairytale world. He's touched most of the other characters' lives in one way or another, and he almost always gets what he wants. Most notably, he is the one who created the curse that brought everyone to Storybrooke — though he intentionally created the catch that allowed Emma to break the curse.
Despite being the Dark One, Rumplestiltskin was capable of love, and he fell in love with Belle after taking her on as a servant. However, he didn't believe she could love him back, and her threw her out; Queen Regina told him she later died (a lie), breaking his heart.
In Storybrooke, Mr. Gold is a rich wheeler and dealer, who uses his wealth and power to intimidate and manipulate the townsfolks (he claims they fear him even more than Regina). He's always one step ahead, and is loyal to no one but himself. During Season 1, he was one of the few characters who remembered the Fairy Tale world, and he has an intense animosity towards Regina.
Relatives: Baelfire (son), Milah (wife)