The term "pirate" is rather loose, and often intermixed with privateer. The British suffered heavily from American privateer's, but considered them to an extent to be more pirates than privateers.
There were the Barbary coast pirates who terrorized the Med, England, France and as far as Denmark. Does that also make the Vikings pirates? From the Wiki article:
Code of laws
Once she held the fleet's leadership position, Ching Shih started the task of uniting the fleet by issuing a code of laws.[7]:28 The Neumann translation of The History of Pirates Who Infested the China Sea claims that it was Cheung Po Tsai that issued the code.[8] Yuan Yung-lun says that Cheung issued his own code of three regulations, called san-t'iao, for his own fleet, but these are not known to exist in a written form.[4] The code was very strict and according to Richard Glasspoole, strictly enforced.[9]
First, anyone giving their own orders (ones that did not come down from Ching Shih) or disobeying those of a superior was beheaded on the spot.
Second, no one was to steal from the public fund or any villagers that supplied the pirates.[4]
Third, all goods taken as booty had to be presented for group inspection. The booty was registered by a purser and then distributed by the fleet leader. The original seizer received twenty percent and the rest was placed into the public fund.
Fourth, actual money was turned over to the squadron leader, who only gave a small amount back to the seizer, so the rest could be used to purchase supplies for unsuccessful ships.[4][7]:39 According to Philip Maughan, the punishment for a first-time offense of withholding booty was severe whipping of the back. Large amounts of withheld treasure or subsequent offenses carried the death penalty.[7]:29
Ching Shih's code had special rules for female captives. Standard practice was to release women, but J.L. Turner witnessed differently. Usually the pirates made their most beautiful captives their concubines or wives. If a pirate took a wife he had to be faithful to her.[10] The ones deemed unattractive were released and any remaining w
ere ransomed. Pirates that raped female captives were put to death, but if pirates had consensual sex with captives, the pirate was beheaded and the woman he was with had cannonballs attached to her legs and was thrown over the side of the boat.[4][7]:29[10]
Violations of other parts of the code were punished with flogging, clapping in irons, or quartering. Deserters or those who had left without official permission had their ears chopped off, and then were paraded around their squadron. Glasspoole concluded that the code "gave rise to a force that was intrepid in attack, desperate in defense, and unyielding even when outnumbered."[9]
So that's not exactly what we might consider to be a "pirate". Once a group, like the Barbary Pirates, or Ching Shih, they really begin to become quasi-governmental entities and nations in their own right. Though that's probably more of a philosphical discussion that doesn't belong here.
Oh, and one other thing, towards the label of "most successful pirate ever", the full quote - "She is widely considered to be the most successful pirate in history, based on the fact that she commanded the largest crew ever assembled, and that she died in her own bed as a free woman." She was a successful pirate, but did she loot more money than pirates who preyed on Spanish Galleons? I don't know. I find the final part - "...and that she died in her own bed as a free woman." to be telling. Most pirates died in the carrying out of their duties. The Barbary pirates stayed at home and had crews doing their dirty work for them, making them more like crime bosses than possible what a pirate is. Again we get into the philosphical area.