Revelation 19:9 says blessed are those invited to the marriage supper of whom?

Answer: The Lamb

The angel told John to write: "Blessed are those who are invited to the marriage supper of the Lamb."

“Then the angel told me to write, “Blessed are those who are invited to the marriage supper of the Lamb.” And he said to me, “These are the true words of God.””— Revelation 19:9 (BSB)