The actor Michael Sheen has founded a new initiative aimed at providing "fairer alternatives" to mainstream rent-to-own firms and payday lenders.
The End High Cost Credit Alliance aims to create a "social movement" that brings together 50 partners.
It will invest in not-for-profit companies to "compete and win against" high-cost credit providers.
The Consumer Finance Association, which represents payday lenders, said they had "strong affordability rules".
Sheen told the BBC's Victoria Derbyshire programme the alliance will tackle "those who unfairly target the most vulnerable in society".
The actor - who has appeared in films including Frost/Nixon and The Queen - describes himself as an activist and has taken on roles as a Unicef ambassador and patron of Social Enterprise UK.
'Shift in the sector'
Sheen said the initiative would focus on helping those who are excluded from mainstream credit, and see high-cost credit as the most attractive alternative.
In 2016, the Victoria Derbyshire programme's investigation into rent-to-own retailer BrightHouse, conducted by former Labour leader Ed Miliband, highlighted the example of a £358 washing machine that ended up costing more than £1,000.
In 2015, the Financial Conduct Authority (FCA) imposed a cap on payday loan costs following criticism of lenders.
But the actor said he also wanted to see "a shift in the whole sector, that benefits both the borrowers and the lenders".
The alliance will invest in not-for-profit organisations that provide "fairer alternatives" for low-income families, helping improve public awareness of their work and enable them to compete with "high-cost credit competitors".
In bringing together more than 50 voluntary members, including representatives of think tanks, public health bodies and credit experts, it also hopes to create a "social movement" that leads to change.
It aims to drive change to policy and regulation, and help improve financial education for young people.
Sheen said he had been focused on the alliance for a couple of years, and had used his own money to finance it after hearing a "pattern emerging" - through his work with support organisations and charities - of the difficulties those using high-cost credit providers had faced.
The Financial Conduct Authority said it engaged with "a wide variety of groups, such as the End High Cost Alliance, to ensure credit is sensibly available to those with lower incomes and means. We want to see more options and the emergence of 'mid-cost credit'."
The CFA said it was clearly not the case "that every payday loan user was vulnerable".
It added that there were now "protections in place, such as a price cap and strong affordability rules that will reduce the chances of [customers] getting into trouble".
A spokesman for BrightHouse said: "We are proud to offer a service to people with low incomes and poor credit histories; the people others are unwilling to serve. For example, we can fit a brand new washing machine into a customer's home for just £3 a week."
Watch the BBC's Victoria Derbyshire programme on weekdays between 09:00 and 11:00 on BBC Two and the BBC News Channel.