Poll: Favorite Frequent Acting Collaborations

There are many actors whose best work comes from the collaboration with a fellow actor, one usually of similar demeanor and personality. They bring out the best in one another, and we can never get enough of them together. So from the list below, which of these frequent acting collaborations, or 'duos', would you say is your all-time favorite? Note: I will be excluding comedic duos, like Abbott & Costello, trying to focus solely on recurring acting collaborations. Also, in order to qualify, at least 3 films must be shared between the actors. After voting, you may discuss the poll here.