Kicking off the summer box office in style, Disney and Marvel Studios' The Avengers earned $18.7 million in Thursday midnight runs, a record for a superhero title and the eighth best of all time.

As The Hollywood Reporter reports, The Dark Knight grossed $18.5 million in midnight runs on its way to a weekend debut of $158.4 million in 2008 -- the second-best domestic opening of all time behind Harry Potter and the Deathly Hallows Part 2, which earned $43.5 million in midnight runs last summer (the best ever) and $169.2 million for the weekend.

The tentpole feature, which unites key Marvel superhero characters, is widely predicted to clear $150 million in its domestic debut. It is the first Marvel title marketed and distributed by Disney since it bought Marvel.

The Joss Whedon-directed 3D film already has earned $300 million overseas in slightly more than a week of play, topping the total lifetime grosses for Iron Man ($267 million), Thor ($268 million) and Captain America: The First Avenger ($192 million) -- whose characters also are in Avengers. It should eclipse Iron Man 2 ($311.5) by Saturday at the latest.

In North America, the movie is outpacing all previous Marvel films -- including the Spider-Man franchise -- in terms of advance ticket sales, as well as last year's Transformers: Dark of the Moon, according to online ticketing service Fandango.

Spider-Man 3, debuting on the same early-May weekend in 2007, opened to $151.1 million (then the biggest debut of all time domestically).

In terms of weekend records, only three other films have hit $150 million or more after Spider-Man: this year's The Hunger Games ($152.5 million), The Dark Knight ($158.4 million) and crown-holder Harry Potter and the Deathly Hallows: Part 2 ($169.2 million).