"Jack" the Monkey

"Why thank ye, Jack."

"Your Welcome."

"Not you! We named the monkey Jack"

-Barbossa talking to both "Jack" the monkey and Jack Sparrow.

"Jack" the Monkey was the monkey that was owned by Hector Barbossa It is unknown how Barbossa obtained the monkey.

=Barbossa's Pet=

"Jack" the monkey was traveling with Barbossa for quite a while. He was cursed by the curse of the Aztec Gold, so it is believed he took a piece along with the rest of the pirate crew.

He snatched the final piece of Aztec Gold from William Turner when Will's father, "Bootstrap Bill" Turner, sent the last piece of Gold to his son. "Jack" the monkey brought back the piece of gold to Barbossa, who thanked the monkey. This was when the two Jacks got confused.

Cursed Again
Once Barbossa was killed, "Jack" took a piece of gold out of the re-sealed chest. He was therefore re-cursed.