There are many bromances in Hollywood - Fallon and Timberlake, Matt Damon and Ben Affleck, Channing Tatum and Jonah Hill, etc.. One bromance that seemed to develop quickly, and doesn't get as much press, is the friendship between Harry Styles and James Corden.

Since 2015, 'Styden' has been a very underrated bromance. Styles has even hosted The Late Late Show on numerous occasions when Corden needed a fill-in at the last minute. He very kindly hosted the show when Corden's wife went into labor with their third child.

The two first met early in Styles' career, through Harry's former bandmate, Louis Tomlinson. Tomlinson's mom worked on a British television show that Corden starred in during the 2000s.

After Tomlinson appeared on The X Factor, he hung out with both Styles and Corden...and Harry and James hit it off.

The pair have hung out together on and offscreen. They've gone on vacation together, attended birthday parties and hung out with other famous celebs.

Their friendship has been compared to that of Justin Timberlake and Jimmy Fallon - JT is another former boy bander and Jimmy is a late-night show host. Harry and James have the same type of chemistry (and quick wit) as JT and Jimmy.

Read on for 15 little known facts about Harry Styles and James Corden's friendship.

15 Corden Has Been Very Supportive Of Styles Throughout His Career

Since the 1D days, Corden has been a Directioner. He has been supportive of all the 1D boys but is especially close to Harry. He promoted both of Harry's solo albums, has had him on his show many times and has generally supported him in every way possible. Styles has also supported Corden, so this friendship isn't a one-way street.

RELATED: Surprising Facts About Our Fave Host James Corden 

14 They Are Good Friends With Adele

The three celebs all went on vacation together. They visited a Caribbean island just a few months ago. Corden and Adele met in an airplane hanger in Wales, while Styles knows Adele through show business. Harry met her while recording his debut solo album. Who wouldn't want to be in that friend circle?

13 Styles Hangs Out With Corden And His Family

On a family trip to New York, Styles shops with the Cordens and hangs out with them. He helped push the stroller across the street. Styles even folded the stroller of Corden's son, Max, and put it into the back of a taxi. Jokes were made that Corden's wife, Julia, was third-wheeling. They are one big, happy family.

12 'The Late Late Styles' Was The First Of Its Kind On The Show

His week-long residency on the show started the tradition. To promote his debut solo album, Styles spent a week on The Late Late Show. His time on the show was filled with performances, monologues, sketches, Carpool Karaoke, and so much more. This week really showcased the Brits' friendship and how they riff off each other.

11 They Have Shown PDA On Multiple Occasions

After attending a concert with Corden and his wife, the pair hold hands, which they have done on multiple occasions. The men are not shy about showing affection to each other and that is something more men should embrace. They are just good friends who hold each other's hands sometimes and generally show affection to each other.

10 Styles Was One Of The Few Guests To Drive On 'Carpool Karaoke'

Usually, Corden drives and cranks up the tunes, but during the pre-taped recording in December, while Corden was promoting Cats, Styles filled in and took the front seat during the sketch. It just felt like two friends actually carpooling to work together and hopefully, there's be more Carpool Karaoke with Styles in the future.

RELATED: 15 Surprising Facts About James Corden's Carpool Karaoke

9 Styles Has Guest-Hosted More Than You Remember

If you count the 'Late, Late Styles' stint, Styles has hosted the show 3 times. He filled in for Corden when his wife was going into labor and when James was away promoting "Cats." Styles has proven, between this and his SNL runs, that he is a great comedian who should have his own talk show one day.

8 He Made His First Appearance On The Show In 2015 With One Direction

Right after Zayn Malik left the group, the band made their debut appearance without him. Corden asked Styles if they were looking for another bandmate, hinting towards himself, but Styles made it clear (as a joke) that they were good.

This appearance included the infamous dodgeball sketch, plus Carpool Karaoke and tattoo roulette.

7 Styles Has A 'Late, Late' Tattoo

When the 1D boys appeared on the show, Harry got the short end of the stick and had to get inked with the show's logo. Styles lost the round of tattoo roulette and had to get 'Late, Late' tattooed on his body. He has over 50 tattoos, so it was no sweat for him.

Plus, it is a nod to his friendship with Corden. It's something he will have forever unless he gets it lasered off someday.

RELATED: 19 Photos of Harry Styles' Best and Worst Tattoos

6 Corden Fakes His Tattoos

To poke fun at his friend getting the tattoo on the show, Corden did a magazine shoot with fake tattoos. Doing a cover shoot for WSJ magazine, Corden sported random tattoos that had no meaning. Many people thought they were real, but Corden actually doesn't have any tattoos.

5 They Have Done Carpool Karaoke Four Times

Styles has done Carpool Karaoke probably more than anyone - twice by himself to promote both of his albums, once with One Direction, and once for a Christmas special. For the Christmas special, a bunch of celebrities got together and sang "Santa Claus is Coming to Town." It's always a great time with these two.

4 They Shared Margaritas At James' Birthday Party

To celebrate Corden's 40th birthday in 2018, the friends drank margaritas poolside. Hanging out in Cabo, Mexico, the friends relaxed in the sun. If bringing your friend to another country for your birthday isn't friendship goals, we don't know what is. This is not the first time Styles has joined Corden on trips.

3 They've Kissed Twice (That We Know Of)

James Corden got to do twice what every Harry Styles fan can only dream of doing. During his first solo Carpool Karaoke, the two friends liplock. The second time they smooched was during the Christmas special. We love to see two men who are confident in their sexuality and can express affection.

2 James' Parents Love Harry

Hanging out with Mr. and Mrs. Corden at the Superbowl, Styles danced salsa (he took on the woman's part) as they fangirled over him. We imagine that James and Harry's relationship is so close that Styles is like another son to the Corden's. What a way to celebrate his 26th birthday!

1 Harry Lived With Corden's Late Late Show Producer

When his career was taking off, Styles lived in Ben Winston's home. Winston is Corden's producer and Harry lived in his attic for 18 months. Winston was the genius behind some of One Direction's iconic music videos.  There was even a show called "Happy Together" that was loosely based off of this scenario. The show only lasted one season.

NEXT: A Dive Into Harry Styles' Career, In 20 Pictures