Shelley's mainstream following did not develop until a generation after his death, unlike Lord Byron, who was popular among all classes during his lifetime despite his radical views. For decades after his death, Shelley was mainly appreciated by only the major Victorian poets, the pre-Raphaelites, the socialists, and the labour movement. One reason for this was the extreme discomfort with Shelley's political radicalism, which led popular anthologists to confine Shelley's reputation to the relatively sanitised "magazine" pieces such as "Ozymandias" or "Lines to an Indian Air".
He was admired by C. S. Lewis, Karl Marx, Robert Browning, Henry Stephens Salt, Gregory Corso, George Bernard Shaw, Bertrand Russell, Isadora Duncan, Constance Naden, Upton Sinclair, Gabriele d'Annunzio, Aleister Crowley, and W. B. Yeats. Shelley had an enduring and profound influence on the Dutch poets of "De nieuwe Gids" (Kloos, Van Eeden e.a.). Samuel Barber, Sergei Rachmaninoff, Roger Quilter, Howard Skempton, John Vanderslice, and Ralph Vaughan Williams composed music based on his poems.
Critics such as Matthew Arnold endeavoured to rewrite Shelley's legacy to make him seem a lyricist and a dilettante who had no serious intellectual position and whose longer poems were not worthy of study. Arnold famously described Shelley as a "beautiful and ineffectual angel". This position contrasted strongly with the judgement of the previous generation who knew Shelley as a sceptic and a radical.
Many of Shelley's works remained unpublished or little known after his death, with longer pieces such as A Philosophical View of Reform existing only in manuscript until the 1920s. This contributed to the Victorian idea of him as a minor lyricist. With the inception of formal literary studies in the early twentieth century and the slow rediscovery and re-evaluation of his oeuvre by scholars such as Kenneth Neill Cameron, Donald H. Reiman, and Harold Bloom, the modern idea of Shelley could not be more different.
Paul Foot, in his Red Shelley, has documented the pivotal role Shelley's works—especially Queen Mab—have played in the genesis of British radicalism. Although Shelley's works were banned from respectable Victorian households, his political writings were pirated by men such as Richard Carlile who regularly went to jail for printing "seditious and blasphemous libel" (i.e. material proscribed by the government), and these cheap pirate editions reached hundreds of activists and workers throughout the nineteenth century.
Shelley's poem, "To the Queen of My Heart", was allegedly forged and falsely attributed to Shelley by James Augustus St John, who took over as editor of the London Weekly Review when Carlile was imprisoned in 1827.
In other countries such as India, Shelley's works both in the original and in translation have influenced poets such as Rabindranath Tagore and Jibanananda Das. A pirated copy of Prometheus Unbound dated 1835 is said to have been seized in that year by customs at Bombay.
Paul Johnson, in his book Intellectuals, describes Shelley in a chapter titled "Shelley or the Heartlessness of Ideas". In the book, Johnson describes Shelley as an amoral person, who by borrowing money which he did not intend to return, and by seducing young innocent women who fell for him, destroyed the lives of everybody with whom he had interacted, including his own.
In 2005 the University of Delaware Press published an extensive two-volume biography by James Bieri. In 2008 the Johns Hopkins University Press published Bieri's 856-page one-volume biography, Percy Bysshe Shelley: A Biography.
The rediscovery in mid-2006 of Shelley's long-lost "Poetical Essay on the Existing State of Things", as noted above, was slow to be followed up until the only known surviving copy was acquired by the Bodleian Library in Oxford as its 12-millionth book in November 2015 and made available online. An analysis of the poem by the only person known to have examined the whole work at the time of the original discovery appeared in the Times Literary Supplement: H.R. Woudhuysen, "Shelley's Fantastic Prank", 12 July 2006.
In 2007 John Lauritsen published The Man Who Wrote Frankenstein, in which he argued that Percy Bysshe Shelley's contributions to the novel were much more extensive than had previously been assumed. It has been known and not disputed that Shelley wrote the Preface—although uncredited—and that he contributed at least 4,000–5,000 words to the novel. Lauritsen sought to show that Shelley was the primary author of the novel.
In 2008 Percy Bysshe Shelley was credited as the co-author of Frankenstein by Charles E. Robinson in a new edition of the novel entitled The Original Frankenstein published by the Bodleian Library in Oxford and by Random House in the US. Robinson determined that Percy Bysshe Shelley was the co-author of the novel: "He made very significant changes in words, themes and style. The book should now be credited as 'by Mary Shelley with Percy Shelley'."
In late 2014 Shelley's work led lecturers from the University of Pennsylvania and New York University to produce a Massive open online course (MOOC) on the life of Percy Shelley and Prometheus Unbound.
In popular culture
- Shelley is believed to have been the model for Marmion Herbert, one of two male protagonists in Benjamin Disraeli's 1837 novel Venetia; the other, Lord Cadurcis, being based on Lord Byron.
- Henry James's 1888 novella, The Aspern Papers relates a struggle to obtain some letters by Shelley years after his death. It was made into a stage play and an opera.
- Spoon River Anthology by Edgar Lee Masters (1915) includes a poem Percy Bysshe Shelley as the namesake of the speaker, whose ashes "were scattered near the pyramid of Caius Cestius / Somewhere near Rome."
- Howard Brenton's play, Bloody Poetry (1984), explores the complex relationships and rivalries between Shelley, Mary Shelley, Claire Clairmont, and Byron.
- Shelley's cremation at Viareggio and the removal of his heart by Trelawny are described in Tennessee Williams's 1953 play Camino Real by a fictional Lord Byron.
- A visit to Lord Byron's estate by Shelley and Mary Shelley is the setting for Ken Russell's 1986 film Gothic.
- A fictional Shelley befriends cavalry officer Matthew Hervey in the 2002 Allan Mallinson novel A Call to Arms.
- Novelist Julian Rathbone fictionalises Shelley in A Very English Agent (2002), wherein a 19th-century government spy tampers with the poet's boat, causing his death.
- Shelley appears as himself in Peter Ackroyd's novel The Casebook of Victor Frankenstein (2008).
- Shelley was played by Ben Lamb in Shared Experience's 2012 production, "Mary Shelley" by Helen Edmundson, at the Tricycle Theatre, London.
- Shelley's poem "Love's Philosophy" appears frequently in the second season of the mystery television series Twin Peaks.
- Shelley's poem "Ozymandias" lends its name to an episode of Breaking Bad. AMC had a teaser trailer for the final season of the show in which Bryan Cranston reads the poem.
- Shelley is portrayed in Blackadder's third-season episode "Ink and Incapability" as one of Samuel Johnson's admirers. He is played by Lee Cornes.
- In the novel "Six oies cendrées" (2001), French author Henri Coulonges gives a fictional account of the provenance of the mystery baby girl Elena Adelaide Shelley in Naples as the daughter of Elise Foggi.
- The last line of Stanza LIII of Shelley's elegy of John Keats, Adonais "No more let Life divide what Death can join together." is referenced a number of times by major characters in the Showtime/Sky Victorian horror series Penny Dreadful.
- Some of Shelley's poems are mentioned in the detective videogame L.A. Noire, where they are used for solving a series of murders.
- During the 2017 elections in the United Kingdom, Jeremy Corbyn frequently quoted the final stanza of Shelley's 1819 poem, The Masque of Anarchy, which begins, "Rise like lions after slumber, in unvanquishable number!" The words came to be used by Corbyn supporters as a sort of unofficial battle cry.