I have come across the worst poem ever written, and, surprise, it wasn't by Macgonagall. It's called A Tragedy, and it's by Theophilus Marzials. It was published in 1874.
Warning! Before clicking on the link, clear your desk or immediate vicinity of hot or cold beverages. Any fluids currently residing in your mouth are liable to exit via your nasal passages on reading the first lines of this poem.
OK? If you think you can handle it, click on this link.