How many Fictional Jacks can we come up with?

Each person can only post one at a time, and must wait until someone else posts to post another.

Jacks from nursery rhymes and fables are preferred, but other jacks are acceptable so long as they are wholly fictional.

I'll start.

The Jack of Hearts.

Jack the giant killer.

Jack Frost

Jack be Nimble.

ah crap, only one...let me delete and post again then....

Jack Horner.

Jack of the beanstalk.

Jack Sprat

you know that peter peter pumpkin eater *wanted* to be called Jack don't you?

Interesting factoid...
Jack o'lantern. Must be named after a guy, right?

Aha, info on 'Jack-o'-lantern'...
"Despite the colourful legends, the term jack-o'-lantern originally meant a night watchman, or man with a lantern, with the earliest known use in the mid-17th century; and later, meaning an ignis fatuus or will-o'-the-wisp.[7] In Labrador and Newfoundland, both names "Jacky Lantern" and "Jack the Lantern" refer to the will-o'-the-wisp concept rather than the pumpkin carving aspect."

Interesting.

So, does mine still count? If you read the fairytales, he appears to be a character...

"An old Irish folk tale tells of Stingy Jack, a lazy yet shrewd farmer who uses a cross to trap the Devil. One story says that Jack tricked the Devil into climbing an apple tree, and once he was up there Jack quickly placed crosses around the trunk or carved a cross into the bark, so that the Devil couldn't get down. Another myth says that Jack put a key in the Devil's pocket while he was suspended upside-down.

Another version of the myth says that Jack was getting chased by some villagers from whom he had stolen, when he met the Devil, who claimed it was time for him to die. However, the thief stalled his death by tempting the Devil with a chance to bedevil the church-going villagers chasing him. Jack told the Devil to turn into a coin with which he would pay for the stolen goods (the Devil could take on any shape he wanted); later, when the coin/Devil disappeared, the Christian villagers would fight over who had stolen it. The Devil agreed to this plan. He turned himself into a silver coin and jumped into Jack's wallet, only to find himself next to a cross Jack had also picked up in the village. Jack had closed the wallet tight, and the cross stripped the Devil of his powers; and so he was trapped. In both myths, Jack only lets the Devil go when he agrees never to take his soul. After a while the thief died, as all living things do. Of course, his life had been too sinful for Jack to go to heaven; however, the Devil had promised not to take his soul, and so he was barred from hell as well. Jack now had nowhere to go. He asked how he would see where to go, as he had no light, and the Devil mockingly tossed him an ember that would never burn out from the flames of hell. Jack carved out one of his turnips (which was his favourite food), put the ember inside it, and began endlessly wandering the Earth for a resting place. He became known as "Jack of the Lantern", or Jack-o'-Lantern."
(Thanks to wikipedia, font of all knowledge.)

what about Jack from JACK and JILL?

Cap'n Jack Sparrow..."savvy?"

Jack O'Neill!
(finally watching SG1, am I)

Jack Ketch

Jack Tar

Jack...it's a boat, Jack! Jack, it's a boat! Jack! A boat, Jack!

(I think you all know who I'm talking about. have no idea what the character's last name was, though.)

um...*puts hand up* I don't get the reference, sorry..

Jack of All Trades (Master of None)

I suppose not everyone had a little sister who was obsessed with Titanic. I refer to this Jack, whose surname (as the internet informs me) is "Dawson".

Jack Ryan

(also, on a nosy tangent, why haven't you made it to World's End yet? it's very nice there, if you can get past the basic level of insanity. )

Jack Dandy.

World's End...as in 'PoTC: At World's End'? I've seen the movie (can't believe they're dragging it out for a fourth movie!)...or are you referring to something in the Forum somewhere?

Apathy is talking about the social part of the forum.

Jack who jumped over the candle stick.