The I Know What You Did Last Summer cast features Madelyn Cline, Chase Sui Wonders and Jonah Hauer-King. This info article contains minor spoilers and character details for Jennifer Kaytin Robinson’s 2025 movie on Amazon and Netflix. Check out more cast guides in Vague Visages’ Know the Cast category.

I Know What You Did Last Summer takes place in Southport, North Carolina. One year after covering up a crime, Danica Richards and her friends reunite for a wedding. The narrative follows the main protagonists as they get targeted by a killer. Here’s every actor and character in I Know What You Did Last Summer, a sequel to the 1998 sequel film I Still Know What You Did Last Summer and the fourth film in the movie franchise.

Read More at VV — Know the Cast: ‘I Know What You Did Last Summer’

I Know What You Did Last Summer Cast: Madelyn Cline as Danica Richards

Character Profile: A wealthy resident of Southport, North Carolina. Her fiancé gets murdered one year after she covered up a crime with friends. Danica feels guilty about forcing her friends to lie.

Cline’s Resume: Taylor Watts in Vice Principals (2016-17), Tina in Stranger Things (2017), Sarah Cameron in Outer Banks (2020-), Whiskey in Glass Onion: A Knives Out Mystery (2022), Heather Mulgrew in The Map That Leads to You (2025)

Read More at VV — Know the Cast: ‘Fear Street: Prom Queen’

I Know What You Did Last Summer Cast: Chase Sui Wonders as Ava Brucks

Character Profile: Danica’s best friend. She hooks up with true crime podcaster while returning home to Southport. Ava unknowingly angers an estranged friend.

Wonders’ Resume: Makayla in Daniel Isn’t Real (2019), Emma in Bodies Bodies Bodies (2022), Nikki in Bupkis (2023), Sam in City on Fire (2023), Quinn Hackett in The Studio (2025-)

Read More at VV — Know the Cast: ‘Until Dawn’

I Know What You Did Last Summer Cast: Jonah Hauer-King as Milo Griffin

Character Profile: Ava’s ex-boyfriend. He lands a political job in Southport. Milo gets strangled by a masked killer.

Hauer-King’s Resume: Laurie Laurence in Little Women (2017), Eric in The Little Mermaid (2023), Lali Sokolov in The Tattooist of Auschwitz (2024), Lieutenant Commander Robert Reeves in A House of Dynamite (2025), Connor Blake in The Threesome (2025)

Read More at VV — Know the Cast: ‘War of the Worlds’

I Know What You Did Last Summer Cast: Tyriq Withers as Teddy Spencer

Character Profile: Danica’s first fiancé. His father is a wealthy entrepreneur. Teddy struggles emotionally after accidentally killing a man with his vehicle.

Withers’ Resume: Connor Tibbs in The Game (2021-22), Tim in Tell Me Lies (2022), Aaron in Atlanta (2022), Yates Skurk in Me (2024), Cam in Him (2025)

Read More at VV — Know the Cast: ‘Dangerous Animals’

I Know What You Did Last Summer Cast: Sarah Pidgeon as Stevie Ward

Character Profile: Danica and Ava’s estranged friend. She reunites with her former inner circle of friends after leaving rehab for a drug addiction. Steve protects a dark secret.

Pidgeon’s Resume: Jane Cartwright/Jane Doe in Gotham (2019), Leah Rilke in The Wilds (2020-22), Young Clare in Tiny Beautiful Things (2023), Maeve in Lazareth (2024), Val in The Friend (2024)

Read More at VV — Know the Cast: ‘Clown in a Cornfield’

I Know What You Did Last Summer Cast: Billy Campbell as Grant Spencer

Character Profile: Teddy’s father. He is a fishing entrepreneur who gets accused of covering up crimes to protect Southport’s reputation. Grant gets murdered by a masked killer.

Campbell’s Resume: Cliff in The Rocketeer (1991), Quincey P. Morris in Dracula (1992), Mitch Hiller in Enough (2002), Darren Richmond in The Killing (2011-14), John Cardinal in Cardinal (2017-20)

Read More at VV — Know the Cast: ‘Ash’

The I Know What You Did Last Summer cast also includes:

• Sarah Michelle Gellar as Helen Shivers
• Freddie Prinze Jr. as Ray Bronson
• Jennifer Love Hewitt as Julie James
• Brandy Norwood as Karla Wilson
• Gabbriette as Tyler
• Austin Nichols as Pastor Judah
• Nick Farnell as Chief Roberts
• Joshua Orpin as Wyatt
• Georgia Flood as Hannah Decker
• Nick Hardcastle as Neal

Q.V. Hough (@QVHough) is Vague Visages’ founding editor.