As for big actors in lesser known but great films/roles
Kevin Spacey in The Life of David Gale
Kevin Bacon, Gary Oldman, Christian Slater in Murder in the First
Sleepers. Brad Pitt, Robert Deniro, Dustin Hoffman, Minnie Driver, Ron Eldard
Z for Zachariah with Chris Pine, Chiwetel Ejiofor and Margot Robbie
The cast of A Time to Kill. Matthew Mcconaughy, Sandra Bullock, Samuel L Jackson, Kieffer Sutherland, Ashley Judd, Donald Sutherland. Also had a ton of actors that are recognisable by face if not by name. Oliver Platt, Charles Dutton, Chris Cooper, Doug Hutchinson.
The Cider House Rules with Michael Caine, Tobey Mcguire, Charlize Theron, Paul Rudd, JK Simmons,
The weirdest though has to be Stephen King in Sons of Anarchy