Who played Dennis Reynolds in 'It's Always Sunny in Philadelphia'?

In which TV series is Dean Winchester a main character? Who played Michael Scofield in 'Prison Break'? In which TV series is Michael Scofield a main character? Who played Charlie Kelly in 'It's Always Sunny in Philadelphia'? In which TV series is Dennis Reynolds a main character? Who played Frank Reynolds in 'It's Always Sunny in Philadelphia'? In which TV series is Frank Reynolds a main character? Who played Nancy Botwin in 'Weeds'?