Sounds like a Vigilante with the Warlock archetype would be a good place to start.
Agreed that Warlock would be a good starting point.
Did you want to include the dagger? Might can include something kind of similiar
Devil contracts are probably the closest thing you can do. Unfortunately there is no written way for you to get these contracts. The Asmodian spell "Spellcasting contract" basically lets you give away spellslots so long as they follow the terms of a contract. The spell Conditional Favor lets you give a buff so long as they follow conditions you set. Metamagic Fleeting spell lets you dismiss otherwise undismisable spells. IE: temporary Resurrection. Planar Parchement gives you benefits for writing out a contract for planar binding. It is possible that your dm will allow you to get a devil familiar or cohort to prepare devil contracts for you though in general this is a bad idea.
I don't think vigilante fits Mr gold he is the most powerful dark magic user in the entire setting.
I'd make him a sorcerer honestly, charismatic and a powerful magic user
Alchemist would be the other option. That gives you potions and you could use swords which he does. But your magic wouldn't be as strong and your manipulations wouldnt be a strong early on. Later the wealth of skill ranks makes up for this.
I don't think vigilante fits Mr gold he is the most powerful dark magic user in the entire setting.
I'd make him a sorcerer honestly, charismatic and a powerful magic user
Alchemist would be the other option. That gives you potions and you could use swords which he does. But your magic wouldn't be as strong and your manipulations wouldnt be a strong early on. Later the wealth of skill ranks makes up for this.
Well, are we trying to literally remake him, or is it more about making a character *inspired* by him?
Personally, when I go for a concept based on a fictional character, I don't try for a literal remake.
If *that* was the goal, I'd actually think oracle would be the best fit. Charisma-based, cursed, access to geas/quest, mark of justice, bestow curse, etc.
Edit: Or a Witch or Shaman with a dark patron/spirit.
Sadly, I haven't been able to watch the show. I jumped at the thread due to my love of fairy tales, however. (What was your last concept?)
Just reading your description, I see a couple of things about this character. Foremost, I hope you plan to make him outstandingly Lawful. Someone who makes a lot of money through contracts actually keeps them. And surely he's not Good. A contract is a contract, regardless of who it beggars.
In fact, I'd like to suggest that he probably is a devotee of Asmodeus. He may or may not be outright Evil himself -- he may be what Asmodeus thinks of as a work in progress. He may have another name for his deity; I feel sure somehow that Asmodeus has several names he can legitimately go by. Or Mr. Gold may be quick to tell people that the Prince isn't all that bad. Alternatively, of course, he may be willing to sell his grandmother's grave (with her in it), if the price is right. And then show up at the local desecrated shrine to thank Asmodeus for the deal. However Mr. Gold sees it, I just feel sure that Asmodeus knows about him and is counting on gathering him in some day.
Sadly, I don't know how to use this angle for building the character, but in case someone else does, I'm mentioning it. But I do have some suggestions to look at for class.
First, there's the Investigator class (ACG). The mutagens & bombs of the alchemist may not suit this guy, and the investigator gets the extracts. He's also very good with words, and gets some nifty Knowledge-based class features. Like an alchemist, they get their class level as a bonus to Craft (alchemy), and protection when working with poisons. Sadly, it's not a spontaneous class like sorcerer. Still, it's my favorite based on your description.
Or, if you're talking sorcerer & bard because you want spontaneous magic, you might look at Arcanist (ACG) for a hybrid between prepared & spontaneous magic, with a MAD build that looks at both Int & Cha for its features. Unfortunately, the class doesn't provide any alchemy-based features. (Btw, I've seen School Understanding recommended as a great exploit, while Metamagic Knowledge leading to the greater version sure looks terrific.)
Finally, Lore Oracle (APG) might be a surprise candidate. It's a way for a Charisma-based spontaneous caster (and we love Diplomacy for this guy, of course) to do great at Knowledges. You might especially like it with the Enlightened Philosopher or Seer archetype (Ult Magic). Again, no alchemy features, however.
All three of these classes get all of the Knowledge skills as class skills, something that I'd think Mr. Gold would find helpful at one time or another.
He is the most powerful magic user but that isn't saying much... All the really big magic was magic items really. I don't think anyone even had higher than 6th level spells though admittedly there are definitely artifacts. That's why I went with warlock. Recognizable spells- telekinesis, dimension door, disguise/alter self, magic missile, fireball, form of the dragon(maybe III), that's all I remember. Do note that literally nobody can cast plane shift. If he wants to do it with a full caster great an arcanist fits perfectly. Otherwise Warlock Vigilante will let him do everything I remember Mr. Gold doing. Also it has the fun benefit of literally giving him alternate identities for Mr Gold and The Dark One
Potions could fill in for alchemy for you. There actually is a fair amount of support for it. Cayden Fighting Tankard + Accelerated Drinker + Potion Glutton = 3 potions per round
There are several traits that make charisma skills int based if you want to be less MAD. Pragmatic Activator, Bruising Intellect, Clever Wordplay, ....think I'm missing 1 or 2
Vigilante has pretty good social talents that would help out if you don't invest to hard in charisma. I think one even gives the feat Persuasive Bargaining :)
On the oracle side there is a legalistic curse from blood of fiends
the apprentice and the sorcerer both cast gate and the dark curse is more powerful than any 9th level spell.
The wicked witch has casually cast disintegrate and eternal slumber is a grand hex (LV18)
I don't think that it's helpful to try and make a equivalency with pathfinder magic compared to once upon a time magic but saying that no-one casts above 6th level is ridiculous.
Although I do think actually he'd be better as an intelligence based caster since his plans are Machiavellian at times.
A witch would probably be best but if you wanted the fightyness of gold an Occultist would work well with all the magic items that Gold uses.
May I ask how far through the series are you?
Divination Wizard or an Arcanist.
For all the social Skills take Student of Philosophy which lets you add INT to Diplomacy and Bluff.
You can craft magic items and scrolls. Rumple was the person who wrote the Dark Curse for Evil Queen on a scroll.
Everything else is really just Roleplay and Fluff.
Becoming the Dark One undoubtedly gave Mr. Gold a few mythic tiers as well as centuries of life to reach a fairly high level in whatever classes he has. At low levels, based on the flashbacks, he would probably be an Expert. He would have retrained into appropriate PC classes when he became the Dark One.