Jamieson, Fausset and Brown on Revelation 2:8

8. 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 Re 1:17, 18. As death was to Him but the gate to life eternal, so it is to be to them (Re 2:10, 11).