Revelation 2:8

We now proceed to the second epistle sent to another of the Asian churches, where, as before, observe, I. The preface or inscription in both parts. 1. The superscription, telling us to whom it was more expressly and immediately directed: To the angel of the church in Smyrna, a place well known at this day by our merchants, a city of great trade and wealth, perhaps the only city of all the seven that is still known by the same name, now however no longer distinguished for its Christian church being overrun by Mahomedism. 2. The subscription, containing another of the glorious titles of our Lord Jesus, the first and the last, he that was dead and is alive, taken out of Rev 1:17, Rev 1:18. (1.) Jesus Christ is the first and the last. It is but a little scantling of time that is allowed to us in this world, but our Redeemer is the first and the last. He is the first, for by him all things were made, and he was before all things with God and was God himself. he is the last, for all things are made for him, and he will be the Judge of all. This surely is the title of God, from everlasting and to everlasting, and it is the title of one that is an unchangeable Mediator between God and man, Jesus, the same yesterday, today, and for ever.

— Matthew Henry's Concise Commentary (public domain)

Smyrna--in Ionia, a little to the north of Ephesus. POLYCARP, martyred in A.D. 168, eighty-six years after his conversion, was bishop, and probably "the angel of the Church in Smyrna" meant here. The allusions to persecutions and faithfulness unto death accord with this view. IGNATIUS [The Martyrdom of Ignatius 3], on his way to martyrdom in Rome, wrote to POLYCARP, then (A.D. 108) bishop of Smyrna; if his bishopric commenced ten or twelve years earlier, the dates will harmonize. TERTULLIAN [The Prescription against Heretics, 32], and IRENÆUS, who had talked with POLYCARP in youth, tell us POLYCARP was consecrated bishop of Smyrna by St. John. the first . . . the last . . . was dead . . . is alive--The attributes of Christ most calculated to comfort the Church of Smyrna under its persecutions; resumed from Rev 1:17-18. As death was to Him but the gate to life eternal, so it is to be to them (Rev 2:10-11).

— Jamieson-Fausset-Brown Commentary (public domain)