Who is the main villain of 'Avengers: Infinity War'?

Who played Captain America in the Marvel Cinematic Universe? Who played Thor in the Marvel Cinematic Universe? Who played Black Panther (T'Challa) in the Marvel Cinematic Universe? Which was the first film of the Marvel Cinematic Universe, released in 2008? Which film became the highest-grossing film of all time in 2019, before 'Avatar' reclaimed the title in 2021? Who played Wonder Woman in the 2017 film? Who played Superman in 'Superman' (1978)? Who played Spider-Man in Sam Raimi's 'Spider-Man' (2002)?