Prison break series
All In The Family.
It hasn't been on for years, or even in syndication; and people STILL talk about it.
Friends: Their cast earn like 1 million per episode!
The most successful tv show ever would be Full House:)
Kyle XY , Greek , It's always sunny in Philadelphia , Suite life on deck , Dragon ball Z
The most successful television series in terms of franchise, is Doctor Who, because of the money it has made from the series, merchandise, books, novels etc, during the past 46 years.