The Marvel Cinematic Universe is a franchise consisting of film and television adaptations of Marvel Comics publications produced by Marvel Studios. The franchise is notable for being the first superhero film franchise to have characters and plot points from different titles crossover.
Hank Pym is the original Ant-Man, created in the 60's by Stan Lee and Jack Kirby. In the comics, he is a founding Avenger, but in the MCU, he is portrayed by elder actor Michael Douglas. Although he did develop the Ant-Man technology in the 60's, he retires as a superhero after a disagreement with the heads of SHIELD, and later trains Scott Lang to be Ant-Man in order to foil his former mentee's evil plot.