Lauren Bacall and Humphrey Bogart
Not only was Key Largo one of the best movies ever made, it had some of my all-time favorite performances. Every single cast member was extraordinary but I am always especially blown away by Bogie, Bacall, Lionel Barrymore, and Claire Trevor.
Just an outstanding movie with one outstanding performance after another. John Huston was an excellent director and this was one of his best films.
You can find all of the excellence on dvd (Amazon link) or watch Key Largo on Prime Video.