They have scaled Buckingham Palace, thrown flour at the Prime Minister and even donned superhero suits in the name of paternal rights.
But it seems the militantly pro-dad group Fathers 4 Justice has had a change of heart. Now they want to help mothers, too.
After years of confronting mums for denying dads the chance to see their children, the civil rights group is to relaunch as a helpline for all parents whose family lives are in crisis.
The organisation closed officially earlier this month, after the news that a father who had made phone calls to the group had killed himself and his children on Father's Day.
The shutdown has not prevented splinter groups from continuing to campaign, under the name New Fathers 4 Justice. Two weeks ago this faction mounted a homophobic protest against "lesbo dads" in Bristol.
Matt O'Connor, the original organisation's founder, said: "As Fathers 4 Justice, the name did what it said on the tin. But we don't want to be misogynistic. Fathers can be equally as bad as mothers. I want something that's not about gender, not about fathers, but about families. F4J polarised people, but we don't want to do that. We want to bring everyone together."
The new service, which will provide telephone counselling, is likely to be called Family Line, and launch next year as an "SOS service" for families in breakdown.
"I think we can do a lot of constructive work and maybe save lives and prevent tragedy," said Mr O'Connor. "We want our number in every solicitor's office and courtroom across the country. Then we can make a difference in a very different way.
"Since F4J was disbanded, people have said 'the organisation saved my life'. Our ministry had a lot more to it than the flippant humour we deployed in our campaigns. That hid the trauma and the darkness of breakdowns."
As well as the helpline, the organisation is to announce a new, more formal, lobbying group next month called Fathers' Union. Less anarchic than its predecessor, it will bring political pressure on the Government to change the family courts system. "It will be more grown-up and conventional," explained Mr O'Connor. "Suited and booted, with not a superhero in sight.
"I believe that to solve this problem you need to pull together mothers and fathers, brothers and sisters, and have a more inclusive approach. But if we'd called it Parents 4 Parity back then, we wouldn't have got anywhere, so [the name has] served its purpose and now we need new ways of moving things forward."
Part of Mr O'Connor's motivation for the change is his own greatly improved family situation. He sees his sons often and has a good relationship with his former wife. He will be running this latest venture with his new partner, who has experienced the challenges of being a mother of children from a previous marriage.
"My individual story was one of forgiveness and hope. If my ex-wife and I hadn't broken that deadlock by saying sorry and everything, we would still be fighting. We showed that it can be done. But the F4J brand isn't the right way to do that."