THEN AND NOW: The cast of 'Knocked Up' 16 years later

"Knocked Up" was the first time that Rogen had played the lead role in a comedy.

By that point in his career, he had previously only appeared in supporting roles in the likes of "Anchorman: The Legend of Ron Burgundy," "You, Me, and Dupree," and "The 40-Year-Old Virgin," the last of which was also directed by Judd Apatow.

The Canadian actor followed up "Knocked Up" with a series of comedies that he penned with his writing partner, Evan Goldberg, including "Superbad," "Pineapple Express," "This Is the End," and "The Interview."

While he starred in all of these, he also appeared in the films "Step Brothers," "Zack and Miri Make a Porno," "50/50," "Neighbors," as well as many others.

More recently, Rogen appeared in Steven Spielberg's "The Fabelmans" and voiced the character of Donkey Kong in "The Super Mario Bros. Movie."

Heigl's character in the movie is the total opposite of Rogen's and the night after they sleep together, they decide to go their separate ways.

At the time of filming, Heigl was also balancing her role on ABC's "Grey's Anatomy," in which she played Dr. Izzie Stevens, a role she held between 2005 and her exit in 2010, and brought her recognition and many acting accolades, including an Emmy in 2007.

The actor went on to star in movies like "27 Dresses," "The Ugly Truth," "Life As We Know It," "The Big Wedding," and "New Year's Eve."

She also since starred in a number of television series, including the final two seasons of "Suits," "State of Affairs," and Netflix's "Firefly Lane."

After "Knocked Up" was released, Heigl shared in a Vanity Fair interview that while she enjoyed working with Apatow and Rogen, she wasn't particularly proud of the film's messaging as it "paints the women as shrews, as humorless and uptight, and it paints the men as lovable, goofy, fun-loving guys."

Prior to "Knocked Up," Mann appeared in numerous films, including "The Cable Guy," "George of the Jungle," and "Big Daddy."

It was while auditioning for "The Cable Guy" that the actor met her future husband, Judd Apatow, as he was one of the film's producers and read a scene with her as a stand-in for Jim Carrey's character.

Mann, along with Paul Rudd, who plays her husband in the film, reprised their roles for Apatow's "This is 40," a film that followed the characters of Debbie and her husband, Pete.

She has also been seen in "The Bling Ring," "How to Be Single," "Blockers," and "Cha Cha Real Smooth."

When "Knocked Up" was released, Rudd was already a name to know. He had made a memorable turn as Phoebe's boyfriend Mike in "Friends" and had a number of roles under his belt in both comedies and dramas, including "Clueless," "Romeo + Juliet," and "Wet Hot American Summer."

Like Rogen and Mann, he had also previously worked with Apatow on a number of his films, including "Anchorman: The Legend of Ron Burgundy" and "The 40-Year-Old Virgin."

The actor — who still looks the same today as he did 16 years ago — has continued to impress audiences with his performances that oscillate between humorous and moving.

He played a teacher in "The Perks of Being a Wallflower," and acted opposite himself in Netflix's "Living With Yourself." On the comedic side, he has appeared in "Role Models," "I Love You, Man," "Anchorman 2: The Legend Continues," and the aforementioned "This is 40."

However, Rudd is perhaps best known these days as the star of the Marvel film "Ant-Man." Since the film was released in 2015, the actor has gone on to star in several more MCU films, including "Captain America: Civil War," "Ant-Man and the Wasp," and "Avengers: Endgame."

Earlier this year, he returned as Ant-Man for a third movie titled "Ant-Man and the Wasp: Quantumania." Audiences can next see him in the untitled "Ghostbusters: Afterlife" sequel.

While his role in the film is quite small, the same year that "Knocked Up" was released, Hill began making waves in Hollywood thanks to his hilarious performance in "Superbad," which was produced by Apatow and co-written by Rogen.

Prior to that, Hill had only a handful of credits to his name, including small roles in "The 40-Year-Old Virgin," "I Heart Huckabees," "Click" and the television series, "NYPD Blue."

Following the success of "Superbad" and "Knocked Up," Hill joined the casts of several classic comedies, including "Forgetting Sarah Marshall," "Funny People," "Get Him to the Greek," "This Is the End," and the "21 Jump Street" films — which he also contributed to as a screenwriter.

Additionally, the actor has lent his voice to several animated films over the years, such as the "How to Train Your Dragon" series, "Megamind," "The Lego Movie" franchise, and "Sausage Party."

Despite his wide success in comedy, Hill also became known for his work in dramatic films. Most notably, he appeared in "Moneyball" and "The Wolf of Wall Street," both of which earned him Oscar nominations for best supporting actor.

In 2018, he wrote and directed the film "Mid90s." and more recently, Hill starred in the Netflix films "Don't Look Up" and "You People."

Segel is another actor whose relationship with Apatow goes way back and like Rogen and Mann, he starred in the Apatow-produced series, "Freaks and Geeks."

When "Knocked Up" was released, Segel had only appeared in low-budget films such as "Slackers," "SLC Punk!," "The Good Humor Man," and "Dead Man on Campus."

Segel portrayed the lovable lawyer on the critically acclaimed CBS series which ran for nine seasons between 2005 and 2014.

He also starred in the comedy films "Forgetting Sarah Marshall," "The Five Year Engagement," "The Muppets," and "Sex Tape."

Outside of acting, Segel is a New York Times bestselling author and co-authored a trilogy of young adult novels titled "Otherworld," "OtherEarth," and "OtherLife."

His most recent role has been opposite Harrison Ford in the Apple TV+ series "Shrinking," and he also starred in last year's HBO series "Winning Time: The Rise of the Lakers Dynasty."

Baruchel landed his first acting job when he was 12 so by the time he appeared in "Knocked Up," he was no stranger to movie sets. Most memorably, he appeared in the Oscar-winning films "Almost Famous" and "Million Dollar Baby."

He was also cast on Apatow's acclaimed yet short-lived television series "Undeclared," alongside Seth Rogen, Carla Gallo, Charlie Hunnam, and Monica Keena.

The actor followed up "Knocked Up" with roles in cult-classic comedies like "Tropic Thunder," "She's Out of My League," and "This Is the End." He also voiced Hiccup in the popular "How to Train Your Dragon" series.

Later this year, Baruchel will appear in a biopic film about the history of the BlackBerry line of mobile phones, simply titled "BlackBerry."

Maude, who is the eldest daughter of Apatow and Mann, played Sadie, the young daughter of Debbie and Pete who can't quite wrap her head around the fact that Ben has joined the family for breakfast the night after his and Alison's one night stand.

Maude's younger sister Iris also appears in the scene, playing Charlotte.

Following her debut in "Knocked Up," she again appeared alongside her sister as the daughter of Mann's character in "Funny People," and "This Is 40," in which she reprised her role as Sadie.

She also had a recurring role as Cleo in the fourth season of the HBO series "Girls" and appeared in the Ryan Murphy series "Hollywood," before she became known for portraying Lexi Howard on Sam Levinson's teen drama "Euphoria."

Her film roles include "Assassination Nation" and "The King of Staten Island," and she has also appeared on the stage in the shows "Little Shop of Horrors" and "Cabaret."