Who is the Bride of the Messiah?

"And there came unto me one of the seven angels which had the seven vials full of the seven last plagues, and talked with me, saying, Come hither, I will shew thee the bride, the Lamb's wife."  (Revelation 21:9) "Let us be glad and rejoice, and give honour to him: for the marriage of the Lamb is come, and his wife hath made herself ready.  And to her was granted that she should be arrayed in fine linen, clean and white: for the fine linen is the righteousness of saints." (Revelation 19:7-8)