Heidegger's Bible Handbook: Malachi: Author

1.  The last Prophet is מַלְאָכִי/Malachi.  He is not Malchiah, or Ezra, or Zechariah.

In the choir of the Prophets the last is מַלְאָכִי/Malachi, which means my Angel;[1] Malachi was not a heavenly Angel, as Origen raved:  or that מַלְכִּיָּה/ Malchiah, of whom mention is made in Ezra 10:25, 31; Nehemiah 3:11; 8:4:  or Ezra the Priest, as some Hebrews and other assert, supported by the argument, that below the Priest of the Lord, of which sort was Ezra, is called an Angel,[2] although Ezra is called a Priest, but never a Prophet:  or Mordecai, as some vainly speculate:  or Zechariah the Prophet, as our Bibliander divines from this, that Zechariah is also called a messenger; but he is a particular Prophet, whose name was Malachi, born, if confidence can be given to the doubtful narration of Epiphanius, in the town of Sopha, in the tribe of Zebulun.

[1] מַלְאָךְ/malach signifies angel or messenger.

[2] Malachi 2:7.