"Ender's Game," Harrison Ford's science fiction return to the big screen, easily topped the North American Box Office on its debut weekend, official figures released Monday showed.

The film, which depicts a battle to save humans from an alien attack, took $27 million in theaters, knocking wacky Jackass comedy "Bad Grandpa," ($20 million) into second place, said industry tracker Exhibitor Relations.

"Last Vegas," starring Michael Douglas, Robert De Niro, Morgan Freeman and Kevin Kline, on a seniors' bachelor party in Sin City, entered in third spot, taking $16.3 million, with animated comedy "Free Birds," ($15.8 million) in fourth.

"Gravity" -- with Oscar winners Sandra Bullock and George Clooney as astronauts adrift in space after a devastating accident -- scored $12.8 million in fifth spot, taking its gross takings to nearly $219 million.

"Captain Phillips," based on a true story and starring Tom Hanks as a cargo ship captain captured by Somali pirates, earned $8.4 million.

Steve McQueen's "12 years a Slave" earned $4.8 million between Friday and Sunday, jumping from last week's eighth place to seventh, edging out "Cloudy With A Chance of Meatballs 2," which took $4.2 million.

"The Counselor" with Michael Fassbender, Penelope Cruz, Cameron Diaz, Javier Bardem and Brad Pitt, earned $3.4 million but fell from fourth place to ninth spot on its second week in theaters.

The reprise of "Carrie," the latest film adaptation of the Stephen King horror tale about an outcast schoolgirl out for revenge, rounded out the top 10 -- earning $3.3 million, but falling from last week's sixth place.