It (miniseries)

It is a 1990 supernatural horror miniseries directed by Tommy Lee Wallace, adapted by Lawrence D. Cohen from the Stephen King novel of the same name.
Plot.
The story revolves around an inter-dimensional predatory shapeshifter which has the ability to transform itself into its prey's worst fears, allowing it to explore the phobias of its victims. It mostly takes the form of a sadistic, wisecracking clown called Pennywise, in order to trick and murder children. The protagonists are The Lucky Seven, or The Losers Club, a group of outcast children who discover Pennywise and vow to destroy him by any means necessary. 
The series takes place over two different time periods, the first when the Losers first discover Pennywise as children, and the second when they're called back as adults to defeat Pennywise, who has resurfaced.
Cast.
The series features an ensemble cast, which includes Dennis Christopher, Annette O'Toole, John Ritter, Harry Anderson, Richard Thomas, Tim Reid, Richard Masur, Michael Cole, Olivia Hussey, and Tim Curry as Pennywise.
Background.
Originally thought as a four-part eight-hour series, ABC enlisted writer Lawrence D. Cohen to adapt the 1,138-page King novel. Production on "It" began in early 1990, and the series was filmed over a period of three months in New Westminster, British Columbia in mid-1990. 
Aftermath.
"It" aired on ABC over two nights on November 18 and 20, 1990, and was a major success for the network, attracting 30 million viewers in its premiere. Since its initial television broadcast, the miniseries has gotten positive reception and becoming a cult sensation following in recent years.