An Over the Shoulder shot is one of the most common shots in film and television. It frames a dialog speaker with the shoulder and back of the head of the character being spoken to. Along with the Medium Two-Shot, it is one component of the Shot/Reverse Shot. A classic tactic for Double Vision. Sometimes used as a variant of The Faceless.
The video game trope Always Over the Shoulder is named for this. See Over-the-Shoulder Murder Shot for a horror-specific Sub-Trope.