The Grady Girls from The Shining might be the most famous from the horror genre, but there are many others that terrify. By the way, in Stephen King book, the girls were never given any names.
In TV, the concept of twins was multiplied exponentially with the terrific Orphan Black series that turned Tatiana Maslany into a star. It's well deserved I might add.
Collider has a nice article devoted to this concept.
Elias and Lukas from Goodnight Mommy are up there too.
But an underrated horror movie that has a set of twins (Emily and Gabriel) that I really loved was James Wan's Malignant.
The last few scenes when one twin is incarcerated was really frakking fun.
Open thread below...
