Who played Tony DiNozzo in 'NCIS'?

Who played Marissa Cooper in 'The O.C.'? Who played Charlie Harper in 'Two and a Half Men'? Who played Alan Harper in 'Two and a Half Men'? In which TV series is Alan Harper a main character? Who played Abby Sciuto in 'NCIS'? In which TV series is Abby Sciuto a main character? Who played Jack Shephard in 'Lost'? Who played Kate Austen in 'Lost'?