William Pengelly was born on January 12, 1812, in East Looe, Cornwall, England.

He was a British geologist and amateur archeologist. As the son of a sea captain, he left school at the age of 12 to join his father's crew. Returning to Looe while still in his teens, he spent his time reading widely and learning mathematics. In 1836, he moved to Torquay and opened a day school teaching according to the fashionable Pestalozzian method. In 1846, he gave up his successful school to become a private tutor and started lecturing on various scientific subjects, a career he continued for the rest of his life. He had a particular interest in caves and cave faunas and was responsible for the excavation of the Brixham Caves, Devon. In 1849, Pengelly published his first scientific paper on fossil fish found in East Cornwall. This was the first of some 120 papers on geology, paleontology, and human prehistory he would publish. His desire to educate led him to found the Torquay Young Men's Society (later the Torquay Mechanics' Institute), the Torquay Natural History Society, and in 1862, the Devonshire Association for the Advancement of Literature, Science, and Art (now The Devonshire Association). He also contributed papers to the Transactions of the Royal Geological Society of Cornwall. He was elected a Fellow of the Royal Society and the Geological Society.

In 1838, he married Mary Ann Mudge (1817–1851), and in 1853, he married Lydia Esther Spriggs (1819–1898). He died on March 16, 1894, in Torquay, Devon, England.