Helga Rooney is the main antagonist of the Liv and Maddie episode, "Halloween-a-Rooney". She is the fictional third Rooney sister and like Liv and Maddie, Helga is portrayed by Dove Cameron.
Helga's only appearance is in Halloween-a-Rooney. She appears when Maddie wishes on a magic amulet. Maddie's wish was to not be a twin anymore and that resulted in Helga's creation. During the time Helga was around, Helga was shown to be feared by everyone in the Rooney home and Ridgewood High and for good reason. Later, Maddie wished to be a twin again, but instead of Helga disappearing, Liv disappeared, leaving Helga and Maddie. Eventually, Maddie wished for everything to return to normal and in doing so, she found that she had just been dreaming the whole time.
Unlike Liv and Maddie, Helga has a twisted personality. Helga is very intimidating and has a habit of torturing her family and friends. Helga will even put people in cages if they disobey her, as shown during Helgafest, which was originally known as Screamfest before Helga took it over. Helga often refers to herself in the third person and she even has a demonic voice.
Helga has telekinesis, allowing her to move things without actually touching them. She mainly uses this power to give Helga Wedgies to people who disobey her.
- Helga's existence changed the "sisters by chance, friends by choice" poster to one that says, "Sisters by chance, friends by force." In this poster, Liv and Maddie are seen kneeling to Helga.
- Helga has a love of fish and can eat fish in three seconds.
- Helga has very strong teeth, as she ate the amulet while it was covered in hummus and it didn't seem to bother her.