It, by Stephen King, was published in 1986. The novel won the British Fantasy Award in 1987, and received nominations for the Locus and World Fantasy Awards that same year. Publishers Weekly listed It as the best-selling book in the United States in 1986.

A miniseries based on the book aired in 1990.

If you want a good scare for Halloween, I highly recommend both the book and the miniseries.  But be warned you may never feel the same way about clowns or balloons ever again.

The terror, which would not end for another 28 years-if it ever did end-began, so far as I know or can tell, with a boat made from a sheet of newspaper floating down a gutter swollen with rain. ~ It by Stephen King

Read the book or view the miniseries.