Stephanie Butler

Stephanie Butler (Laura Clifton) is the main villainess in the alternate ending of the 2017 horror-comedy film, Happy Death Day. She is married to Dr. Gregory Butler, a hospital physician as well as a professor at Bayfield University.

Happy Death Day
Dr. Butler was also revealed to be an adulterer, as he was having an affair with one of his students, Theresa "Tree" Gelbman. However, another girl and a nurse at Bayfield’s hospital, Lori Spengler (the film's main villainess), also sought to have an affair with Dr. Butler and attempted to kill Tree. In the actual film, Stephanie appeared briefly and was introduced to Tree by Dr. Butler after she nearly caught the two kissing, with lingering looks from Stephanie seemingly implying she was aware of (or at least had suspicions of) her husband's infidelity.

Original ending
In the film's alternate ending (the intended original one), Stephanie turned heel and plotted vengeance towards Tree, after she learned about Greg's affair with her. The scene had Tree hospitalized after fighting off Lori, who spent the movie trying to kill her while Tree was able to survive due to being stuck in a time loop. After being left alone by her father and boyfriend Carter Davis, Stephanie entered the room disguised as a nurse and prepared to inject Tree, claiming it was "for the pain."

As Tree told her that her doctor hadn't put her on pain medication, the evil Stephanie unmasked herself and stated that it would be for her pain, angrily asking Tree if she thought she was going to get away with sleeping with her husband. As Tree bemoaned the fact that she was about to be killed permanently after surviving death ten times, Stephanie injected the syringe into Tree's IV, killing Tree and cementing Stephanie's heel turn.

Trivia

 * The original ending for Happy Death Day was shown in test screenings for the film, and was received negatively by the audience, forcing the writers to come up with the theatrical one in which Stephanie isn't a villainous character and is oblivious to Gregory’s infidelity.

Quotes

 * “(Tree: “Excuse me, what are you doing?”) It's for the pain. (Tree: “The doctor said no pain medication.”) Not your pain, Theresa. Mine. Did you really think you'd get away with screwing my husband?” (Stephanie snarling at Tree as she poisoned her in the original ending)