Revelation 1:18

ἐγενόμην is emphatic in intentional contrast to ἐγώ εἰμι ὁ πρῶτος, and still more to ζῶν εἰμί, setting His temporal and temporary death against His eternal life; see on Revelation 1:4.

τοῦ θανάτου καὶ τοῦ ἅδου. Hades is the receptacle of the dead: usually personified in this book, as indeed is death, Revelation 6:8; Revelation 20:13-14. But here they are rather conceived as places, prisons wherein the dead are confined, and from which Christ can deliver them. We read of “the gates of death “in Psalms 9:13; Job 38:17; and “the gates of hell” in Isaiah 38:10; Matthew 16:18.