The story follows a group of sorority sisters who receive threatening phone calls and are eventually stalked and murdered by a killer during the Christmas season.

Inspired by the urban legend "the babysitter and the man upstairs" and a series of murders that took place in the Westmount neighbourhood of Montreal, Quebec, Moore wrote the screenplay under the title Stop Me.

Jess and the other sorority members listen as the caller rants and screams in strange voices, referring to someone called "Billy", before abruptly threatening to kill them.

Upset by the call, a younger student named Clare Harrison decides to leave and goes upstairs to her bedroom to pack her suitcase.

As Jess watches the singers, the killer sneaks into Barb's room and stabs her to death with a glass unicorn figurine, with her cries for help being drowned out by the carolers.

[7] Film producers Harvey Sherman and Richard Schouten had Timothy Bond rewrite the script to give it a university setting.

[10] Clark sought Keir Dullea to play the role of Peter based on his performance as Dave Bowman in 2001: A Space Odyssey (1968).

She accepted the part, but dropped out one month before filming began owing to Saturday Night Live commitments, and was replaced by fellow Second City comedy troupe performer Andrea Martin.

Upon his arrival to the set, however, the producers realized he would be unable to fulfill the duties required of the part due to his failing health (stemming from Alzheimer's disease).

For the role of the film's antagonist, Italian-Canadian actor Nick Mancuso was cast as one of the main voices in the phone call sequences.

According to Griffin, her character's surprise as the killer lunges from the closet was genuine as the actress later recalled: "It was a total shock because I didn't really know when to expect him to jump out!"

Shots of Clare's corpse in the rocking chair required the actress to wear an actual plastic bag over her head for extended periods of time.

[8] Mancuso stated in an interview that he stood on his head during the recording sessions to compress his thorax and make his voice sound more demented.

[7] During preparation in 1975 for the film's American release, Warner Bros. studio executives asked Clark to change the concluding scene to show Clare's boyfriend, Chris, appear in front of Jess and say, "Agnes, don't tell them what we did" before killing her.

[11] Clark has stated in an interview that he came up with the film's official title, saying that he enjoyed the irony of a dark event occurring during a festive holiday.

The film was released on 20 December, but only earned $284,345 during its theatrical run due to competition from The Godfather Part II and The Man with the Golden Gun.

On Tuesday, January 24, NBC-TV gave several of its affiliates in Florida, Georgia, and Alabama, the option of showing an alternate film, Doc Savage: The Man of Bronze, in place of Stranger in the House.

[30] The report revealed that "the network said in a statement issued yesterday in New York City that it was responding to concern voiced by the affiliates because of the murder of two coeds this month in a sorority house at Florida State University in Tallahassee".

[32] The following year, on December 3, 2002, Critical Mass released a Collector's Edition of the film on DVD with making-of documentaries, two audio commentary tracks, and reversible English and French cover artwork.

[33] On December 5, 2006, Critical Mass released a third "Special Edition" DVD with a newly remastered transfer, two original scenes with newly-uncovered vocal tracks, a new documentary on the making of the film, and cast and crew interviews.

It contains the same transfer of the film as the "Special Edition" release and all previous bonus content, plus the addition of a new documentary ("Black Christmas Legacy"), a 40th-anniversary panel from Fan Expo 2014, a new commentary track featuring Nick Mancuso as the character "Billy", a new retrospective booklet written by Rue Morgue Magazine, and new packaging art by Gary Pullin (art director of Rue Morgue Magazine).

[39] Variety called the film "a bloody, senseless kill-for-kicks feature, [that] exploits unnecessary violence in a university sorority house operated by an implausibly alcoholic ex-hoofer.

Its slow-paced, murky tale involves an obscene telephone caller who apparently delights in killing the girls off one by one, even the hapless house-mother".

[40] Gene Siskel of the Chicago Tribune gave the film 1.5 stars out of 4 and called it a "routine shocker" that "is notable only for indicating the kind of junk roles that talented actresses are forced to play in the movies".

[41] Kevin Thomas of the Los Angeles Times wrote: "Before it maddeningly overreaches in a gratuitously evasive ending, Black Christmas (opening today at selected theaters) is a smart, stylish Canadian-made little horror picture that is completely diverting ...

The website's critics consensus reads: "The rare slasher with enough intelligence to wind up the tension between bloody outbursts, Black Christmas offers fiendishly enjoyable holiday viewing for genre fans".

67 in IndieWire's The 100 Best Horror Movies of All Time, its entry stating that "the plot sounds formulaic, but Black Christmas remains timeless thanks to its terrifying and elusive killer, 'Billy', whose backstory is never revealed, as well as a foreboding ending that doesn't offer much hope for the film's Final Girl".

[62] While director Clark maintained he did not intend for the film to have political leanings, critics have noted Black Christmas is nonetheless a feminist film for its treatment of female characters—particularly Jess having agency and making the choice to have an abortion—and its portrayal of casual misogyny (as when the police initially fail to take the sorority's concerns about the phone calls and Clare's absence seriously).

Because of this, the novel ends up fleshing out the characters more, adding scenes and lines of dialogue that were initially cut from the film's final script, and giving the Pi Kappa Sigma property more backstory.

[76][77][78] On May 1, 2023, it was announced that It's Me, Billy Chapter 2 had begun crowdfunding on Indiegogo and that original film stars Olivia Hussey and Lynne Griffin would be joining the cast.