I'm referring to the 1st Inquisitor. We have two more coming in SW Rebels this season, and we already know that one of them is named "The Seventh Sister". I'm assuming the other one also has a name. We now know that "Inquisitor" is a title, not a name.
Looking back, I think it was really foolish to have the first inquisitor simply be named "Inquisitor". Imagine if the first police officer you ever met was named "Police Officer" - and every other cop had normal names like Jones, or Smith. You'd always go back to that first guy named "Police Officer" and wonder how silly his tombstone would look.