In my paper “Elias” as a “Forerunner” in Latter-day Saint Scripture, I show that Joseph Smith and his contemporaries used “Elias” to denote a “forerunner.” Interestingly, this is paralleled by the use of προδρομος in some ancient texts:
Where Jesus, a forerunner (προδρομος) on our behalf, has entered, having become a high priest forever according to the order of Melchizedek. (Heb 6:20 NRSV)
Glory to you, my God, and Lord. Glory to you, together with the exceedingly renowned bearer of God and the honored precursor (προδρομος); and all the holy ones, be glory to you. (The Testament of Solomon [A] 26:10)
John is the forerunner (προδρομος), and that voice the precursor (προδρομος) of the Word; an inviting voice, preparing for salvation,-- a voice urging men on to the inheritance of the heavens, and through which the barren and the desolate is childless no more. This fecundity the angel's voice foretold; and this voice was also the precursor of the Lord preaching glad tidings to the barren woman, as John did to the wilderness. (Clement, Protrepticus 9:3)
