This article contains plot details from the latest book.
Elidyr is one of Tam's bodyguards. He is a dwarf. Elidyr was first mentioned in Book 8.5: Unlocked in Tam's registry file, in the category called Bodyguards. There, it was mentioned that Tam Dai Song has two bodyguards, one of which is Elidyr. Elidyr remains primarily underground and has not shared anything about himself with Tam.
The name Elidyr is Welsh for "Bronze" and "Brass."