Rope top
The person who does the tying in a rope scene, also called the rigger; the term describes a role, not a dominant personality.
Rope top is a common synonym for rigger. Anatomie Studio notes that some people prefer it and cautions against confusing it with dominant, a word that implies a more formal power exchange. Shibari Study defines a rope top simply as the person doing the tying, and its general entry for top describes the active partner, usually paired with a bottom, without any sense of dominance. Japanese has its own words for the role: shibarite, literally the binding hand, is a plain descriptive term (Kinbakuwiki), and in seme-focused play the person conducting the torment is the semete (Shibari Study).