In Revelation 22, who says, 'I am the Alpha and the Omega'?

Answer: Jesus

The one who says "I am the Alpha and the Omega" goes on, "I, Jesus, have sent My angel to give you this testimony."

“I am the Alpha and the Omega, the First and the Last, the Beginning and the End.” “I, Jesus, have sent My angel to give you this testimony for the churches. I am the Root and the Offspring of David, the bright Morning Star.””— Revelation 22:13, 22:16 (BSB)