In which TV series is Abby Sciuto a main character?

Who played Alan Harper in 'Two and a Half Men'? In which TV series is Alan Harper a main character? Who played Tony DiNozzo in 'NCIS'? Who played Abby Sciuto in 'NCIS'? Who played Jack Shephard in 'Lost'? Who played Kate Austen in 'Lost'? In which TV series is Kate Austen a main character? Who played John Locke in 'Lost'?