When Percy Shelley was just nineteen, he co-authored a pamphlet titled The Necessity of Atheism – and was expelled from Oxford for doing so. (Source)
Percy Shelley and his wife Mary (the author of Frankenstein) were vegetarians, which was extremely radical in the early 19th century. Percy Shelley’s main work on vegetarianism, "A Vindication of Natural Diet" (1813), is still important for contemporary vegetarians. (Source)
Percy Shelley wrote many of his greatest works in the year 1819, including "Ode to the West Wind," Prometheus Unbound, "The Mask of Anarchy," and "England in 1819."