Ioan Gruffudd

as William Wilberforce

Romola Garai

as Barbara Spooner

Ciarán Hinds

as Lord Tarleton

Rufus Sewell

as Thomas Clarkson

Youssou N'Dour

as Olaudah Equiano

Benedict Cumberbatch

as William Pitt

Nicholas Farrell

as Henry Thornton

Stephen Campbell Moore

as James Stephen