The developers of websites like StackOverflow and Wikipedia, who made it much easier for people to spend time and energy sharing their knowledge for the good of others.

Also, Bill Gates and Warren Buffet who mobilized (arguably, not counterfactually) the billionaire community to pledge >$500b to charitable giving - after a dinner (cost of $5,000/person, at most?). That is $100,000,000 donated per $1 invested - a great deal. Should inspire other altruists to motivate others to pledge, perhaps by leading by personal example--

Religious communities perhaps (and religion in general)? Like, Jesus? Historically, religion provided somewhat of a moral compass. There are a lot of historical accounts of people doing good deeds, even if it meant their death, because of religious beliefs (For example, Catholic Church saints). Their deeds managed to form (big) followings of like-minded people, people who acted the same. We could say that Jesus Christ is one of the people who shaped our world substantially, to the point of no return, in a lot of different ways, and surely "being good and doing good" is one of them. He inspires a lot of people to do good to this very day.

I'm not sure about other faiths, but Christian Catholic religious leaders (pope, priests, priest orders within the Catholic Church - like Franciscans..) often talk about good, charitable deeds and organize charities often (at least in my country). This compels some of the religious folk to volunteer their time and join humanitarian organizations that stem from the Church (Caritas, for example), join catholic missions (for example, in Africa and South America), do charitable work in their communities and be better (more good in a certain moral sense) people in general.

I also heard some people choose to join certain faiths because they thought they were doing enough good, they were "practicing" their faith instead of just talking.

Although, it seems that religion is influential mainly within its own community. But still.

[I'm giving examples from Catholicism because I'm not sure about other religions]

1) Maybe Nelson Mandela and the ANC? (Long Walk to Freedom) - he influenced a lot of people to do significantly more good.

Counterfactually, he was inspired and supported by the changing international norms, so it is difficult to say whether someone else would have not done the same life-long struggle a few years later.

Still, perhaps if Mandela was born into a post-Apartheid South Africa, he could have solved even more issues (perhaps those that his successors were not able to). This naively assumes Mandela's impact on racial equity in South Africa as a constant that can be added to any baseline.

Then, if everyone waits for someone else to counterfactually struggle for an objective that is important to the waiting one, nothing happens. So, unless one has an excuse of doing something more impactful, they should pursue the goal they consider important (of course, pivoting often, asking for a plenty of constructive criticism on one's impact).

2) Or, are you more looking at examples of those in power advocating for others who are disadvantaged? I see large EA donors, such as Dustin Moskovitz and Cari Tuna.

I am not sure how much credit I would give to these donors' influencers, who advanced the alternative norm of success as effective global care as opposed to as achievement within traditional status structures. There could have been one memorable speech or one memorable experience.

3) The EAF Zurich Ballot initiative is an example of a handful of people (without institutional power themselves) inducing a lot of taxpayers to do slightly more good.

One can argue that counterfactually, not seeing this change elsewhere (in 'comparable' places) and assuming the Zurich's foreign aid situation to remain comparable to other Swiss cities where the aid budget is not chaning, this change would have not happened without the EAF's advocacy.

4) I always admire Banerjee and Duflo and their teams who work to make it prestigious to give money to the poor through research recognizable and recognized by economic elites.

They too contribute to the spread of the EA norm, motivating the likes of Dustin Moskovitz and Cari Tuna to focus on effective care of the world as opposed to exhibiting status by consumption of status products so defined by these products' industries.