I have that beat...
Bonnie and Clyde
The French Connection
The Conversation
Young Frankenstein... Two more.
A Bridge Too Far
Unforgiven
The French Conversation and Conversation were all Hackman... Most of his movie parts were supporting roles, but Hackman was up there with the best of them.
The quick and the Dead.
Damn good role in that.
I would like to add “Crimson Tide” to that list. You had two great actors Denzel Washington and Gene Hackman in opposing roles, in which you could sense the tremendous tension between them while they trade dominant positions in the story line.