Let us remember that this excellent poem is written as a dramatic monologue, which is a poem where one character addresses one or more listeners who remain silent. Thus, when we consider the point of view of the poem, it is clear that it is first person, as is made evident from the reference to "I" and "my" in the opening of the poem:
That's my last Duchess painted on the wall,
Looking as if she were alive. I call
That piece a wonder, now...
It is the Duke's narrative and his personality that clearly dominates and characterises the poem. We are able to see things from his point of view, and of course, as we hear, just as the envoy hears, the Duke's story about what happened to his last duchess, we are left to fill in the gaps of the rather curtailed description we are given, suggesting that the last duchess met a rather more brutal end at the hand of the duke than is overtly suggested.
The dominant point of view is that of the Duke, who is the sole speaker in this famous dramatic monologue. What is unusual about the point of view is that, although the Duke is speaking to a visitor representing the father of his fiancee, the speaker, throughout most of the poem, appears to be looking at the portrait of the beautiful young wife he had murdered. The excellent portrait by Fra Pandolf is so lifelike that the Duke seems to be seeing his living last duchess standing before him. Early in the poem he says, "...and there she stands," and towards the end he says, "And there she stands / As if alive." It is an indication of his insensitive nature that he would even consider showing the portrait to his visitor, whom he had brought upstairs to a private room to discuss the dowry he expected to be brought by the young woman he intends to marry next (unless the visitor is so horrified by this scene and this interview that he urges his master to call the wedding off). It is a further indication of the Duke's wicked character that he would even keep the portrait, or that he would be able to look at it and remember what he had done to a beautiful young woman whose character was as angelic as his description of her reveals.