glossator

noun2

1. •
   One who writes glosses.

   • One to two generations after its copying, an extensive but intermittent interlinear Latin gloss [...] was added[.] [...] The glossator also added a single [Old English] gloss — 2008
2. •
   (historical) A legal scholar of the Middle Ages, (specifically) one who authored glosses on legal texts (especially the Corpus Juris of Justinian), typically distinguished from the later commentators who wrote in extended prose and adopted a more pragmatic form of jurisprudence.