Yet finding them is as easy as checking out their Facebook page where, for every posting about Edward Snowden, Bradley Manning or the GCSB, there are many more on BMX feats, sexual innuendo - and discount shopping vouchers. There is more talk than action, though there's a closed page as well as the public face.
The followers are mostly young - the YouTube videos have catch-all appeal: "We are everywhere, we are everyone ... we will save humanity because we can" goes the Max Headroom-without-the-parody vocoder. Touchstones include monopoly cartels, greedy "banksters" and governments run by shadow masters.
Their ominous sign-off is "Expect us" but in New Zealand they have wielded their disruptive power selectively, sticking to freedom issues such as the GCSB bill, which legitimises domestic spying by our foreign intelligence agency, and the 2011 internet copyright (file sharing) legislation. Last year, when a hacker called @AnonVoldemort took down the website of documentary maker Bryan Bruce, the group pitched in to expose the Madrid-based perpetrator.
One ex-member told the Weekend Herald the range of New Zealand recruits was "mind-blowing", including secondary school idealists, social activists, anti-social hackers, lawyers and business people. They express solidarity on global bulletin boards such as 4chan, where this week's activity won applause.
"There's a few different groups and not all are hacktivists - a lot just want to help [the cause]. A lot are just people with verbal diarrhoea but you can tell the genuine ones."
The IT expert said it was easy to acquire the skills; plenty of websites offer basic hacking tips. "Most of what was done on the National Party sites was just DDoS (distributed denial of service) attacks. It's the equivalent of clicking refresh on the page 1000 times." But as corporates and governments bolster online security and detection capability, the hacktivists' prowess only rises.
If the movement has an Achilles heel it is perhaps its cherished anonymity - anyone can claim allegiance. After Tuesday's attacks, a clip abusing John Key was posted on YouTube by "anonymousnz".
"We don't do abusive messages like that and the clip was deleted," the source said.
The movement had no imminent plans for further activity here. "There is no chain of leadership - it can just be an individual who decides on an operation and he or she organises it.
"Usually when Anonymous decides to take action it's within 12 or 24 hours' notice. There are a lot of problems and legitimate causes going on in the world, not just in New Zealand."