LOS ANGELES - Marvel superhero Thor hammered rivals for a second straight weekend at the North American box office, industry estimates showed Sunday.

“Thor: The Dark World,” the latest blockbuster based on Marvel’s iconic comic book character, took a hefty $38.5 million in its second weekend, figures from Exhibitor Relations showed.

Starring Australian heartthrob Chris Hemsworth as the hammer-wielding son of Odin, the movie is a follow-up to the franchise’s 2011 money-spinning first instalment, “Thor.”

With its strong opening weekend — helped by the phenomenal success of 2012’s $1.5-billion hit “The Avengers,” which saw Thor join forces with other characters — the film has taken in a total of nearly $147 million.

Debuting strong in second place was romantic comedy “The Best Man Holiday,” a sequel 15 years in the making to “The Best Man,” in which the college friends reunite over Christmas and reignite romance and rivalries.

The film, starring Monica Calhoun and Morris Chestnut at the head of an ensemble cast, took in $30.6 million.

“Last Vegas,” starring Michael Douglas, Robert De Niro, Morgan Freeman and Kevin Kline on a seniors’ bachelor party to Sin City, was a distant third, with $8.9 million, while animated comedy “Free Birds” was fourth with $8.3 million.

In fifth, screwball Jackass comedy “Bad Grandpa,” took in $7.7 million in its fourth week.

“Gravity” — with Oscar-winners Sandra Bullock and George Clooney as astronauts adrift in space after a devastating accident — held steady in sixth place with $6.3 million during its third weekend in theaters.

Meanwhile, science fiction blockbuster “Ender’s Game” tumbled to seventh place in its third week. The film, adapted from Orson Scott Card’s 1985 novel and starring Harrison Ford, earned $6.2 million.

The critically acclaimed drama “12 Years a Slave,” regarded as an early contender for Oscars glory, was in eighth with $4.7 million.