Who is the speaker in "Do Not Go Gentle into that Good Night?

The narrator of "Do Not Go Gentle into that Good Night" is a son or daughter speaking to their father.  The last stanza of the poem specifically addresses the speaker's "father," when the speaker asks him to "Curse, bless" them with his "fierce tears."  The entire poem is all about various kinds of people -- wise, good, wild, and grave or serious -- and the fact they these individuals refuse to die quietly; instead, they fight against death and try to live as long as possible.  In the final stanza, however, because the speaker is addressing his or her father, these descriptive lines actually become prescriptive: they become instructions.  The speaker now tells their father to resist death and refuse to go quietly.  The speaker wants their father to cry "fierce tears" because such tears would prove that the father is really fighting.