They each took on the establishment and, eventually, helped secure huge advances in human freedom and social justice.
Many of the issues I have espoused over the past 40 years have been initially dismissed as marginal and have often been demonised, such as my early campaigns for women's and queer liberation, for example.
I have found that it takes a great deal of perseverance, determination and patience to win a campaign. You need to be in it for the long haul and to not expect instant results.
The starting point for any successful campaign is to have a clear vision of what you want to change, why it needs to change and how to make change happen. Set out your goals and plan the means to achieve them.
If you support a cause that is unpopular or off the political radar, think about adapting the tactics of guerrilla warfare, and apply them non-violently. Some guerrilla methods have traditionally enabled the weak to defeat the powerful. Take the success of the tiny, impoverished country of Vietnam in vanquishing the mightiest military superpower in history - the USA - for example.
Drawing on guerrilla theory, analyse the strengths and weaknesses of yourself and your opponents. Play on your strengths and your opponent's weaknesses. Devise ambush tactics to throw off balance the opponents of change. Wage a campaign of attrition to undermine and sap the will of those who defend tyranny and injustice.
Also crucial for a positive outcome are imagination, daring and passion. Don't be predictable. Be prepared to take risks and show creativity in the way you campaign.
The best way to win change is by traditional campaign methods such as writing letters, emails, articles and books, petitions, lobbying MPs, speaking at conferences, TV debates and protest marches.
Sometimes, however, when those in power won't listen to reason and compassion, it is necessary to resort to more confrontational methods. In 1998, when Dr George Carey, the then Archbishop of Canterbury, ignored all requests to meet the gay community, I invaded his pulpit during his Easter sermon and denounced his homophobia. The resultant media publicity grabbed public attention, raised awareness and shamed Dr Carey into curtailing his anti-gay stance.
I see my style of direct action as having a cathartic and catalytic effect. It can help to force open previously closed doors and closed minds.
- Peter Tatchell is a human rights campaigner