15. "They Shall Not Grow Old" (2018) - $17.9 million

Director Peter Jackson went to painstaking lengths to digitally restore and transform 100-year-old archival footage for his powerful documentary on World War I. Jackson restored color and sound to the Great War, something that was previously only known through black and white silent film. The documentary performed well in part because of a release that even transformed the footage into 3D.

14. "Oceans" (2010) - $19.4 million

You'll see a lot of Disneynature documentaries on this list. Pierce Brosnan narrates this 2010 documentary filmed across the world's oceans.

13. "Bowling for Columbine" (2002) - $21.5 million

Michael Moore's provocative documentary about American gun violence (and one of his best) won the Oscar for Best Documentary and broke international box office records for a documentary in 2002.

12. "Won't You Be My Neighbor?" (2018) - $22.8 million

Morgan Neville's portrait of Fred Rogers and "Mister Rogers' Neighborhood" proved to be a crowd-pleasing hit in the summer of 2018 because of the absolute niceness at its heart. Neville in his film explains that Fred Rogers was the rare person who really did not have a dark side, and in "Won't You Be My Neighbor?" it shows. 

11. "An Inconvenient Truth" (2006) - $24.1 million

Davis Guggenheim's documentary spotlighting former Vice President Al Gore's plea to alert the world to the effects of global warming and climate change went on to win two Oscars and earn a sequel.

10. "Sicko" (2007) - $24.5 million

Another Michael Moore movie to crack the list, "Sicko" was Moore's look at the healthcare industry in America compared to other nations, with Moore sailing sick veterans down to Cuba to receive the care they couldn't have had at home.

9. "Katy Perry: Part of Me" (2012) - $25.3 million

This 2012 concert movie followed Katy Perry on her California Dreams World Tour.

8. "One Direction: This Is Us" (2013) - $28.8 million

"Super Size Me" filmmaker Morgan Spurlock directed this concert doc about the then wildly popular British boy group.

7. "Chimpanzee" (2012) - $28.9 million

Tim Allen narrated this Disneynature doc about a three-month old chimp separated from his flock and adopted by another grown male.

6. "Earth" (2007) - $32 million

The first of Disneynature's documentaries, "Earth" was a theatrical version of the popular "Planet Earth" miniseries from 2006. "Earth" was finally given a stateside theatrical release in 2009.

5. "2016: Obama's America" (2012) - $33.4 million

Dinesh D'Souza's anti-Obama documentary speculated about where the country would be if Obama won a second term in office in 2012.

4. "Michael Jackson's This Is It" (2009) - $72 million

The footage in "This Is It" comes from a behind-the-scenes look at preparation for Michael Jackson's 50 shows at London's O2 Arena. It wasn't originally meant to be made into a film, but it provided an intimate look at Jackson in his final days.

3. "Justin Bieber: Never Say Never" (2011) - $73 million

The Biebs holds the spot for the highest-grossing concert film ever and the documentary with the biggest opening weekend of all time.

2. "March of the Penguins" (2005) - $77.4 million

People sure love penguins. Morgan Freeman narrates the nature documentary that opened on just four screens but soon spread into a nationwide hit.

1. "Fahrenheit 9/11" (2004) - $119.1 million

Michael Moore's scathing documentary about President George W. Bush and the aftermath of the 9/11 attacks is the highest-grossing documentary of all time and it isn't even close. The film won the Palme d'Or at the Cannes Film Festival. Opening at over $23 million, the movie at the time opened higher than any other documentary had ever grossed in its lifetime. Moore followed up the film with a documentary about the 2016 election and Donald Trump, titled "Fahrenheit 11/9," which refers to the day after he was elected.