Regardless of whether you loved the latest reboot of I Know What You Did Last Summer or not, there's a whole world of whodunnit slashers that you should check out. With their ability to keep you guessing until the bloody end, these movies have perfected the art of suspense. Today we're exploring 8 seriously killer whodunnit slashers (no spoilers!).

1. ‘A Bay of Blood’ (1971)

Director: Mario Bava

Running time: 1h 24m

• On Rotten Tomatoes, A Bay of Blood has 86% from critics and 62% from the audience.
• On IMDb, A Bay of Blood is rated 6.5/10.

A Bay of Blood may be over fifty years old, but don't let that fool you. This Italian horror greatly influenced the slasher genre with its kill scenes later shamelessly borrowed by the Friday the 13th franchise.

The plot revolves around a series of murders taking place around a bay, with various characters trying to claim ownership of the property.

Available on Kanopy, Plex, Darkroom and Fawesome for free.

2. ‘Black Christmas’ (1974)

Director: Bob Clark

Running time: 1h 38m

• On Rotten Tomatoes, Black Christmas has 71% from critics and 76% from the audience.
• On IMDb, Black Christmas is rated 7.1/10.

Black Christmas is about a group of sorority sisters who are stalked by a mysterious killer during the Christmas holidays.

Bob Clark (who, fun fact, also directed the family-friendly A Christmas Story) directed a genuinely unnerving film with disturbing phone calls, gruesome murders and a shocking ending. The film's “the calls are coming from inside the house” trope has become legendary in horror cinema.

Available on Kanopy and Fawesome for free.

3. ‘Happy Death Day’ (2017)

Director: Christopher Landon

Running time: 1h 36m

• On Rotten Tomatoes, Happy Death Day has 71% from critics and 67% from the audience.
• On IMDb, Happy Death Day is rated 6.6/10.

Happy Death Day combines elements of a slasher film with a time loop. On her birthday, college student Tree Gelbman is murdered, only to wake up and relive the same day repeatedly until she figures out who her killer is.

Available on: Fandango At Home, Microsoft Store, Amazon Video, Apple TV.

4. ‘Scream’ (1996)

Director: Wes Craven

Running time: 1h 51m

• On Rotten Tomatoes, Scream has 78% from critics and 80% from the audience.
• On IMDb, Scream is rated 7.4/10.

Scream tells the story of high school students who become targets of a mysterious killer. The whodunnit element keeps viewers guessing until the final reveal.

Available on HBO Max.

5. ‘Alice, Sweet Alice’ (1976)

Director: Alfred Sole

Running time: 1h 47m

• On Rotten Tomatoes, Alice, Sweet Alice has 71% from critics and 61% from the audience.
• On IMDb, Alice, Sweet Alice is rated 6.4/10.

Following the murder of a young girl, suspicion falls on her troubled older sister. The film establishes a disturbing atmosphere through its religious imagery and the presence of an eerie masked killer.

Available on: JustWatchTV, Kanopy, FlixHouse, Plex, Darkroom and Fawesome for free.

6. ‘You're Next’ (2011)

Director: Adam Wingard

Running time: 1h 35m

• On Rotten Tomatoes, You're Next has 80% from critics and 60% from the audience.
• On IMDb, You're Next is rated 6.6/10.

You're Next is the home invasion slasher that follows a family gathering disrupted by a group of masked killers. With a clever twist on the whodunnit formula, this film stands out for its strong female protagonist and darkly comedic tone.

Available on: Amazon Prime Video, fuboTV.

7. ‘April Fool's Day’ (1986)

Director: Fred Walton

Running time: 1h 29m.

• On Rotten Tomatoes, April Fool's Day has 60% from critics and 48% from the audience.
• On IMDb, April Fool's Day is rated 6.1/10.

April Fool's Day follows a group of college students who gather for a getaway at a friend's mansion. This slasher offers a unique spin on the genre with its clever misdirection and twisty storyline.

Available on: Fandango At Home, Amazon Video, Apple TV, FlixFling.

8. ‘Terror Train’ (1980)

Director: Roger Spottiswoode

Running time: 1h 37m.

• On Rotten Tomatoes, Terror Train has 47% from critics and 37% from the audience.
• On IMDb, Terror Train is rated 5.8/10.

In Terror Train, a group of college students’ costume party aboard a train. However, they are hunted by a killer.

Available on: Hoopla and Plex for free.