Who played George Costanza in 'Seinfeld'?

Who played Dan Conner in 'Roseanne'? Who played Winnie Cooper in 'The Wonder Years'? In which TV series is Winnie Cooper a main character? Who played Murphy Brown in 'Murphy Brown'? In which TV series is George Costanza a main character? In which TV series is Elaine Benes a main character? Who played Cosmo Kramer in 'Seinfeld'? Who played Newman in 'Seinfeld'?