You’d be surprised at how often this question comes up in a pub quiz. The answer was Johanes Gutenberg.
The first printing press was developed in the 15th Century in around 1440 in Germany. He was an inventor who found a way to create multiple copies of the books without having to painstakingly write each one individually by hand.
His press design is the template for printing devices well into the 20th century. In 1450, Gutenberg entered into a partnership with Johann Fust who lent him money to finance the production of a Bible. Gutenberg introduced efficient methods into book production, leading to a boom in the production of texts in Europe — in large part, owing to the popularity of the Gutenberg Bibles, the first mass-produced work. Even so, Gutenberg was a poor businessman, and made little money from his printing system.
The earliest dated specimens of printing by Gutenberg are papal indulgences (notes given to Christians by the Pope, pardoning their sins) issued in Mainz in 1454. In 1455, Gutenberg demonstrated the power of the printing press by selling copies of a two-volume Bible for a price that was the equivalent of approximately three years’ wages for an average clerk, but it was significantly cheaper than a handwritten Bible that could take a single monk 20 years to transcribe.