O Brother, Where Art Thou? is a 2000 comedy film directed by Joel Coen and starring George Clooney, John Turturro, and Tim Blake Nelson, which tells the story of three escaped convicts in the American South during the 1930s.
The title of the movie on the poster was likely created using the "Brothers Bold" font produced by Emigre, which features a titling feature. This font is a commercial one, and more information about it can be found here.