relator

noun

1. One who relates, or tells; a relater or narrator.

   “1655, Thomas Fuller, Church-history of Britain, 1845, J. S. Brewer (editor), Thomas Fuller, The Church History of Britain, Volume 1, page 54, He needs almost a miraculous faith to be able to remove mountains, yea, to make the sun stand still, and sometimes to go back, who will undertake to accord the contradictions in time and place between the several relators of this history.”

   “Glentworth listened to Isabella's account of her interview with intense interest, though he endeavoured, for the relator's sake, to suppress its warmer expression; but he could not forbear to ask many questions, drawing out, more than once, every word uttered by Margarita, and spoken by Isabella...”

2. One who relates, associates, or links things together.
3. A private person at whose relation, or in whose behalf, the attorney-general allows an information in the nature of a quo warranto to be filed.
4. An expression of the identity element of a group as a product of generators, used in a presentation (type of specification) of the group.