Who played Adrian Cronauer in 'Good Morning, Vietnam'?

Who played Mark Watney in 'The Martian'? In which film is Mark Watney a character? Who played John Keating in 'Dead Poets Society'? In which film is John Keating a character? Who played Agent J in 'Men in Black'? In which film is Agent K a character? Who played Captain Steven Hiller in 'Independence Day'? Who played Alonzo Harris in 'Training Day'?