What type of literary work is "My Last Duchess" by Robert Browning?

My Last Duchess:
- My Last Duchess, poem of 56 lines in rhyming couplets by Robert Browning, published in 1842 in Dramatic Lyrics, a volume in his Bells and Pomegranates series.
- It is one of Browning’s most successful dramatic monologues.

Robert Browning: (1812-89)
- One of the major English poets of the Victorian age, noted for his mastery of dramatic -monologue and psychological portraiture. 
- He is famous for his dramatic monologues. So, he is often called the father of dramatic monologue.
- His wife Elizabeth Barrett was also a poet of that time. 

Notable Works:

Books of poems:
- Men and Women 
- Dramatic Lyrics
- The Ring of the Book. 

Other Poems: 
- Bishop Blougram’s Apology
- Christmas-Eve and Easter-Day
- Dramatis Personae
- Fra Lippo Lippi
- Men and Women
- My Last Duchess

Source: Britannica.com