THEN AND NOW: The cast of 'Forgetting Sarah Marshall,' including Russell Brand, 15 years later

Actor Jason Segel was already successful by 2008 due to his work with filmmaker Judd Apatow on shows like "Freaks and Geeks" (1999), and "Undeclared" (2001). Apatow also produced "Forgetting Sarah Marshall."

Segel became a much bigger name after landing the role of Marshall Eriksen in "How I Met Your Mother," which ran for nine seasons from 2005 to 2014.

Segel has gone on to forge a successful career, continuing to work with "Forgetting Sarah Marshall" director Nicholas Stoller on "The Five-Year Engagement" (2012). They also co-wrote "The Muppets" (2011) together.

The 43-year-old star also worked with Apatow again on "This is 40" (2012).

Segel most recently starred as a therapist struggling with grief after the death of his wife in Apple TV+'s "Shrinking" opposite Harrison Ford.

Kristen Bell played Peter's ex-girlfriend, Sarah Marshall. She was already an established star best known for "Veronica Mars," in which she played the titular student-turned-investigator. She also narrated every episode of "Gossip Girl."

One of Bell's most famous roles in recent years is Anna in Disney's "Frozen" (2013) and "Frozen II" (2019), as well as numerous short films made by the studio.

Bell also reprised her role as Veronica Mars in a 2014 movie, which was crowdfunded on Kickstarter in just 11 hours. Fans of the series ultimately donated over $5 million toward the project.

Bell also frequently appears on "Armchair Expert," the podcast cohosted by her husband Dax Shephard and Monica Padman, as well as hosting the "We Are Supported By..." podcast with Padman.

Russell Brand played Sarah Marshall's new rock star boyfriend, Aldous Snow, and the character is the exact opposite of Segel's composer. He later reprised the role in 2010's "Get Him to the Greek."

The actor was better known in the UK as a standup comedian as well as for hosting numerous shows like "Big Brother's Big Mouth" and "Russell Brand's Ponderland."

Brand also presented the MTV Video Music Awards in 2008 and 2009, which is where he met his first wife, Katy Perry.

In recent years, Russell Brand has pivoted to sharing often controversial views on YouTube, and has moved away from movies and television.

In September 2023, Brand was accused of sexually assaulting four women between 2006 and 2013, including one woman who said that they were in a relationship when she was 16.

The allegations came to light as part of an investigation led by British newspapers The Times of London and The Sunday Times, and Channel 4's current investigations program, "Dispatches."

Brand refuted the accusations in a video before the claims were made public.

Mila Kunis played hotel reception clerk, Rachel Jansen, Segel's other love interest in the movie.

Kunis was already a pretty big name by the time she was in "Forgetting Sarah Marshall," having starred in "That '70s Show" since 1998, and as the voice of Meg Griffin in "Family Guy" (1999).

Kunis has worked with some big names in the years since "Forgetting Sarah Marshall," starring opposite Denzel Washington in "The Book of Eli" (2010) and Natalie Portman in "Black Swan" (2010).

Kunis also reunited with Kristen Bell for "Bad Moms" (2016) and "A Bad Moms Christmas" (2017).

In September 2023, the 40-year-old star came under fire alongside her husband, Ashton Kutcher, for writing a letter in support of their "That '70s Show" costar Danny Masterson shortly before he was sentenced to 30 years in prison on two counts of rape.

Comedian Bill Hader also starred in the movie as Brian Bretter, the brother of Segel's character.

Hader was best known for his work on "Saturday Night Live," but had also starred in 2007's "Knocked Up" and played Officer Slater in "Superbad." He also appeared as Rob Slolom in "Tropic Thunder" (2008).

Hader's star power only grew after "Forgetting Sarah Marshall," racking up roles in movies such as "Paul" (2011), "Trainwreck" (2015), "Power Rangers" (2017), and "It: Chapter Two" (2019).

Hader's work as the titular hit man-turned-actor in HBO's "Barry" was met with huge critical acclaim, and he won outstanding lead actor in a comedy series at the Emmys in 2018 and 2019.

Jonah Hill played Matthew Van Der Wyk, a waiter at the hotel Peter, Sarah, and Aldous are staying at.

This was Hill's fourth collaboration with Judd Apatow after working with him on "The 40-year-old Virgin" (2005), "Knocked Up" (2007), and "Superbad" (2007).

Like most of the "Forgetting Sarah Marshall" cast, Hill's career continued to grow after 2008 and he received best supporting actor nominations at the Oscars for his work in "Moneyball" (2011) and "The Wolf of Wall Street" (2013).

Hill is also known for his roles in "21 Jump Street" (2012) and its sequel, "22 Jump Street" (2014).

In July 2023, Hill faced backlash after his ex-girlfriend accused him of being emotionally abusive toward her, and "Zoey 101" actor Alexa Nikolas accused him of forcibly kissing her when she was 16 and he was 24.