A dramatic monologue is a narrative-style poem in which a fictional speaker unwittingly reveals their true character while describing some series of events. “My Last Duchess” is a poem in which a fictional speaker describes the events that took place with his former wife, a woman who is now deceased, because he is looking to remarry. The poem is not autobiographical and does not address Robert Browning’s own life, as the speaker is a duke with a “nine-hundred-years-old-name.” Though this character may be inspired by someone in real life, the duke is a creation of the poet’s imagination. Further, the duke is the only character heard to speak in the poem, though he is speaking to someone present with him in the poem, making this a true monologue rather than a dialogue.

In describing the situation with his “last duchess,” the duke does inadvertently reveal his own horrible and selfish character. He criticizes his last duchess for being “too soon made glad” and for blushing just the same no matter what gift was given to her. She did not reserve her smiles and blushes for her husband alone, and this made him angry. However, he refused to speak to her about the matter because it would have wounded his great pride to do so. Therefore, he “gave commands,” and “all smiles stopped together,” making it sound as though he had her killed so that he could start over with a new wife that would value him more highly. What’s more is that he seems to count her portrait as one of his valued possessions—like his statue of Neptune taming a seahorse—indicating how much he objectifies women and his need for control.

A dramatic monologue is a poem in which a speaker addresses another person who does not answer back. This is why it is a monologue rather than a dialogue. In the course of his speech, the speaker reveals aspects of his personality or situation that he might not be aware of or might prefer to keep hidden.

"My Last Duchess" is a classic example of a dramatic monologue. The duke addresses an emissary who has come to arrange his next marriage. He speaks to him about his dead wife, the "last duchess" of the title. While the duke obviously wants to impress this man, he reveals aspects of his character that are less than flattering.

For instance, he shows himself to have been jealous, narcissistic, and controlling in his relationship with his now dead wife. As they gaze at her portrait, the Duke complains that she would dare to smile at other people and to be happy at simple pleasures. He couldn't bear that she didn't focus exclusively on him, saying:

She had 

A heart—how shall I say?— too soon made glad, 

Too easily impressed; she liked whate’er 

She looked on, and her looks went everywhere. 

Sir, ’twas all one! My favour at her breast, 

The dropping of the daylight in the West, 

The bough of cherries some officious fool 

Broke in the orchard for her

Browning's poem is an excellent example of a dramatic monologue. It is a monologue because the entire poem consists of the words spoken by a single voice, Duke Ferrara's. It is dramatic because it contains the elements of drama, primarily characters, a narrative, physical action, and a physical setting. Through these devices of drama, the poem becomes a scene that could be staged with actors and props.

In the poem, the Duke speaks to another person, perhaps an emissary from the family of his next wife. The listener does not interrupt, but his presence is felt in the poem as the Duke refers to him as "you" and "sir" and offers him a chair so that he may sit and look at the portrait of the Duke's former wife. At the conclusion of his comments, the Duke directs his visitor to leave his seat and move on:

Nay, we'll go

Together down, sir.

As they descend, the Duke points out a bronze statue of Neptune taming a sea horse, symbolic of his relationship with his former wife.

These physical actions (sitting and leaving) and the props (the guest's chair, the portrait of the Duchess, and the bronze statue) make it possible for the reader to visualize the scene as if it were played out upon a stage.

Throughout the Duke's monologue, the story develops, and his character, as well as the Duchess's, is revealed. Her fate at his hands is not established precisely, but the conclusion of the poem (and the story) implies that his next Duchess will be marrying a man who misrepresents himself, concealing the arrogance and cruelty of his nature.