Happy Death Day is a 2017 American black comedy slasher film directed by Christopher Landon and written by Scott Lobdell.

The film follows college student Tree Gelbman, who is murdered on the night of her birthday but begins reliving the day repeatedly, at which point she sets out to find the killer and stop her death.

After a night of drunken partying, Tree Gelbman wakes up on her birthday in the dorm room of classmate Carter Davis.

Before delivering a fatal blow, she realizes that if she kills Tombs and ends the loop, Carter will remain dead forever.

Tree realizes that the previous loop was the only time she ate the cupcake, and she had died in her sleep, thus Lori is her true killer.

The film, initially titled Half to Death, is based on an original story created by screenwriter Scott Lobdell.

"[3] The project was only revived years later, as original producer Angela Mancuso had lunch with Landon and remembered Half to Death.

Landon decided to send the script to Jason Blum of Blumhouse Productions, with whom he had worked in the Paranormal Activity sequels, and he approved it, leading to a green-light by Universal Pictures.

[3] Blumhouse announced the project on October 11, 2016, with Landon directing and Jessica Rothe cast in the lead role of the film.

[4] On November 8, 2016, it was announced that Ruby Modine, Charles Aitken and Rachel Matthews had joined the cast, alongside Rothe and Israel Broussard.

"[7] Scream itself was listed among the influences Christopher Landon took for the film, along with Halloween (1978), Groundhog Day and comedies of the 1980s such as Sixteen Candles and Back to the Future,[8] given he aimed to make a "fun, silly horror movie".

He also aimed to emulate the protagonist's personal growth in Groundhog Day to comment on "this age of social media and all the crappy things that kids do to each other".

[14] The scene after Tree pushes Lori out of the window was supposed to take place at the sorority house, but the filming permit had ended before production was able to shoot there, forcing the location to be changed to a Los Angeles diner.

This version was shown in the test screenings for the film and was received negatively by the audience, which led the writers to create the theatrical ending.

Johnson Berticelli, the mascot's creator, sued Universal Pictures and Blumhouse for copyright infringement, demanding half of the film's profits.

Reflecting the film's blend of horror and comedy, McCreary stated that he wanted "a schizophrenic, dual personality, with light-hearted comedic scoring on one end, and genuinely terrifying soundscapes on the other."

This approach is highlighted by the two main leitmotifs, an energetic theme for Tree evoking contemporary pop music, and one for the killer that consists of distorted vocals provided by McCreary's young daughter Sonatin.

[1] In the United States and Canada, Happy Death Day was released alongside Marshall, The Foreigner and Professor Marston and the Wonder Women, and was expected to gross $15–20 million from 3,130 theaters in its opening weekend.

The website's consensus reads: "Happy Death Day puts a darkly humorous sci-fi spin on slasher conventions, with added edge courtesy of a starmaking performance from Jessica Rothe.

[25] Audiences polled by CinemaScore gave the film an average grade of B on an A+ to F scale, while PostTrak reported 52% of filmgoers rated it as "definite recommend".

noted that although the film makes laudable attempts at merging genres—including romantic comedy, horror and "campus satire"—the end results were mixed.

[26][27] Chris Agar of Screen Rant said that the "fun, if silly, blending of genre tropes ... ends up being a double-edged sword.

[32] Jessica Rothe stated that while most horror sequels retread the original, Landon's pitch instead "elevates the movie from being a horror movie into a Back to the Future type of genre film where the sequel joins us right from where we left off, it explains a lot of things in the first one that didn't get explained, and it elevates everything.