By Steve Gorman

LOS ANGELES (Reuters) - The new Batman movie, "The Dark Knight," swooped into theaters to gross a record $18.5 million from midnight preview screenings ahead of its official opening on Friday, according to distributor Warner Bros.

That tally includes receipts from 12:01 a.m. Friday showings only in 3,040 North American theaters -- 3 a.m. and 6 a.m. screenings were not counted -- and shattered the preview benchmark of $16.9 million set by "Star Wars: Episode III -- Revenge of the Sith" in 2005, the studio said.

The robust advance screenings for "Dark Knight" bolstered projections that the film was headed for an opening weekend of $100 million or more in the United States and Canada.

A $100 million "Dark Knight" debut would more than double the $47 million opening gross averaged by the five previous Batman movies released by Warner Bros, a unit of Time Warner Inc.

Those films have collectively have amassed over $1.6 billion in ticket sales worldwide since 1989, according to box office tracking service Media By Numbers.

The fortunes of "Dark Knight," which cost about $180 million to produce, were further brightened by mostly positive reviews and a record wide release in 4,366 U.S. and Canadian theaters.

"We have been thrilled by the response to 'The Dark Knight,' first from the critics and now from audiences," said Dan Fellman, head of domestic distribution for Warner Bros, in a statement. "From our earliest screenings, the buzz on the film has been white hot, and it hasn't let up."

Box office analysts say the film is almost certain to surpass the $100.1 million debut rung up in May by "Indiana Jones and the Kingdom of the Crystal Skull," which would make "Dark Knight" the biggest opening so far this year.

"Revenge of the Sith," by comparison, grossed $108.4 million in its first Friday-through-Sunday frame from far fewer theaters than "Dark Knight."

The last Batman movie, 2005's "Batman Begins," grossed nearly $49 million its first weekend in North America and went on to collect about $372 million worldwide.

"Dark Knight," picking up where that film left off, reunites director Chris Nolan and star Christian Bale as the Caped Crusader. It also features the late Australian actor Heath Ledger in what turned out to be his last completed screen role, as Batman's arch nemesis, the Joker.

Only 10 other movies have managed to cross the $100 million domestic box-office mark in their first weekends, led by "Spider-Man 3" with $151 million in May 2007 and "Pirates of the Caribbean: Dead Man's Chest" with $135.6 million in 2006, the biggest July opening on record.