William Topaz McGonagall
A minimally educated weaver, he only took to poetry late in life, following an epiphany. He took at once to writing memorable verses, often about his native land, two of the most famous being "Railway Bridge of the Silvery Tay" and "The Tay Bridge Disaster", and walked all the way to Balmoral Castle to obtain the patronage of Queen Victoria.
Although only one book of his works, Poetic Gems, was published during his lifetime, material sufficient for two subsequent volumes was written and published posthumously.
It should be added that McGonagall's fame rests exclusively with the belief of many - including the creator of the website below - that he was the worst poet ever to embarrass the English language!