A character introduced in 'Guardians of the Galaxy' shows up in 'Avengers: Endgame' in a blink-and-you'll-miss-it moment — here's how to find him

Warning: There are major spoilers ahead for "Avengers: Endgame." The fourth "Avengers" outing teams together dozens of Marvel characters on screen. It may be tough to keep track of them all. More »