MALACH (מַלְאָךְ).  Unisex.  Hebrew name, meaning "messenger."

... Jacob speaks of the Malach Jahve who accompanied him and shielded him all through life,... It is further pointed out that Malach originally means not "messenger," but "message," "commission." (Old Testament Theology, Schultz, 1892)

    Though our common term for spiritual messengers is Greek, all the other words for them, as well as the three individual angelic designations that have come into use as baptismal names, are derived from the Hebrew.
    Moreoever, the first of these belonged to the last of the prophets, Malach-jah, the angel or messenger of God.  It has even been thought by some commentators that this title of the prophet was the quotation of his own words, "Behold, I send my messenger (or Malachi) before my face." (History of Christian Names, Yonge, 1884)