Jake Davis, 18, has admitted he and fellow members of LulzSec stole huge amounts of personal data belonging to hundreds of thousands of people and posted it online for anyone to download.
Southwark Crown Court in London heard yesterday that Davis, along with Ryan Ackroyd, Mustafa Al-Bassam and Ryan Cleary considered themselves "modern day pirates", who carried out the attacks for entertainment.
All members of the group, which included a schoolboy and an ex-soldier, have pled guilty to carrying out various acts of cyber crime in 2011.
At a pre-sentencing hearing, prosecutor Sandip Patel said the men lacked the political drive of groups like Anonymous, from which they had developed, and seemed to have been doing it for kicks.
He said: "It's clear from the evidence that they intended to achieve extensive national and international notoriety and publicity. They saw themselves as latter-day pirates.
"This is not about young immature men messing about. They are at the cutting edge of a contemporary and emerging species of criminal offender known as a cyber criminal."
Smartly dressed Davis, 20, from Lerwick, who used the alias Topiary, smirked in the dock when details of his activities were outlined to the court. He was LulzSec's main publicist and in charge of media relations.
Both he and Al-Bassam previously pled guilty to hacking and launching cyber attacks on organisations, including the CIA and the Serious Organised Crime Agency.
Davis's barrister, Simon Mayo QC, told the court his client had completely turned his life around since being arrested.
Born in Canterbury, Kent, he moved to the Shetlands aged six with his mother to escape his alcoholic father, who later committed suicide. Socially isolated from his early teens, Davis suffered from depression and fell under the spell of a "misguided ideology", Mr Mayo said.
But since his arrest, he had moved to London via Lincolnshire and found work with several artistic groups, also writing for the Observer about his time with Anonymous.
Carole Cadwalladr, a feature writer with the paper, provided a reference.
Michael Morris MBE, the co-director of art group Artangel, gave a character reference in court.
"In short, Davis has been given an opportunity he was previously denied, an opportunity to transform himself from a depressed 18-year-old in the Shetland Islands into a self-sufficient scriptwriter living in London," Mr Mayo added, suggesting his client could be given a suspended sentence.
The court heard that the "DDoS" attacks they carried out with other unidentified hackers belonging to online groups such as Anonymous and Internet Feds flooded websites with traffic, making them crash and rendering them unavailable to users.
To do it, they used a remotely controlled network of "zombie" computers, known as a "botnet", capable of being programmed to perform the attack.
The court heard the codes, written by Cleary, may have been using up to one million computers to carry out attacks via the internet without their owners knowing it.
The group only existed for a matter of months in 2011 before the main members were arrested between June and September, the court heard.
Attacks like those on Sony and Nintendo harvested massive amounts of private data. The Sony leak alone saw it lose details relating to 26.4 million customers, causing its Playstation network to shut down.
Davis was found to have 750,000 separate pieces of sensitive data on his computer after his arrest, and Cleary 10,000.
The hearing continues.