Note - these are not just lists of 'famous vegetarians' - they are people with a view on the subject, and the articles explain whether they put those veiws into practice.

• Lord (Thomas) Erskine (1750-1823)
• Sir John Sinclair (1754-1835)
• Joseph Ritson (1761-1803)
• John Abernethy M.D (1763-1831)
• Rev. William Cowherd (1763-1816)
• Dr. William Lambe (1765-1847)
• Sir Richard Phillips (1767-1840)
• John Frank Newton (1770-?1827)
• Robert Southey (1774-1843)
• James Pierrepont Greaves (1777-1842)
• Lewis Gompertz (1779-1865)
• Joseph Brotherton - (1783-1857), became a Bible Christian, Salford's first M.P. (1832), and chaired the first meeting of the first Vegetarian Society (1847)
• Lord (George Gordon) Byron (1788-1824)
• Thomas Forster M.D. (1789-1860)
• William Harvey (1789-1870) - became the second President of the Vegetarian Society in 1859
• Percy Bysshe Shelley (1792-1822)
• Georgiana Fletcher Welch (nee Ford) (1792- ) - patron of The Concordium
• Sophia Chichester (nee Ford) (1795-1847) Patron of The Concordium
• Mary Wolstonecraft Shelley (1797-1851)
• John Smith, (1798-1888) - Fruits and farinacea the proper food of man (link to archive.org) London 1845
• Thomas Hood (1799-1845)
• William Horsell (1807-1863)
• The Bible Christian Church (1809-1930)
• Dr. John Snow (1813-1858)
• A migrant's story (1817)
• Alcott House (1838-1848)
• Roots of vegetarianism
• Salford's first MP
• The earliest known uses of the word 'Vegetarian' - from 1842
  

IVU Manager's blogs:
Veganism from 1806 - a brief timeline summary
Dr. William Lambe - father of vegan nutrition, and his vegan biographer
Dr. Lambe's Rural Roots - his childhood and retirement in Herefordshire
Prototype Vegans - PDF, link to vegansociety.com - written for The Vegan, Winter 2010
John Frank Newton - and the 'vegan' commune of 1813 
Shelley - the first celebrity vegan 
Lewis Gompertz – Jewish ‘vegan’ and co-founder of the RSPCA in 1824 
Taking the Waters - transatlantic pioneer plant-food doctors 
The Vegan School that invented Vegetarians
Vegetarian equals vegan!
Dr. John Snow - a vegan of genius 
The Truth Tester 1846-48 - a vegan journal
The Curious Affair of The Vegetarian Advocate (1848-50)

Complete Old Books:

An Essay on Abstinence from Animal Food (link to archive.org) by Joseph Ritson, published 1802

Joseph Ritson, A Critical Biography (link to archive.org), by Henry Alfred Burd, 1916

Joseph Ritson, Percy Shelley and the making of romantic vegetarianism (link to ucdavis) - essay by Timothy Morton from 'Romanticism 2006

The Code of Health and Longevity Or a Concise View of the Principles Calculated for the Preservation of Health and the Attainment of Long Life. Vol III: (link to archive.org) by John Sinclair, pub 1807.

Facts authentic, in science and religion: designed to illustrate a new tr. of the Bible (link to Google Books) by William Cowherd, 1818

Life of Lord Byron : with his letters and journals (Vol.1 - to 1811) (link to archive.org) pub. London, 1839, this edition 1854. Byron (1788-1824) had a rather inconsistent meatless diet - p.356 (1811): "...an entire vegetable diet, neither fish nor flesh coming within my regimen."

Life of Lord Byron : with his letters and journals (Vol.2 - 1811-13) (link to archive.org) pub. London, 1839, this edition 1854.

Life of Lord Byron : with his letters and journals (Vol.3 1814-17) (link to archive.org) pub. London, 1839, this edition 1854. p.337: abstinence.... like some years ago, ...of diet, and, with the exception of some convivial weeks and days, (it might be months, now and then,) have kept to Pythagoras ever since.

Lord Byron's Don Juan (link to archive.org) first two Cantos pub.1819, unfinished at Canto 16 on Byron's death in 1824. This complete edition from Philadelphia, 1859. Overall it reflects Byron's inconsistency about his diet.

Shelley at Oxford (1810/11) (link to archive.org) - by Thomas Jefferson Hogg, Shelley's friend at Oxford. Originally published as a series of magazine articles in 1832/33. This edition from 1904.

Letters from Shelley to Thomas Jefferson Hogg (1810/11) (link to archive.org) - with notes by W. M. Rossetti and H. Buxton Forman, 1897

Letters from Shelley to Elizabeth Hitchener - Vol.1, 1811 (link to archive.org) - privately printed 1890

Letters from Shelley (& some by Harriet) to Elizabeth Hitchener - Vol.2, 1812 (link to archive.org) - privately printed 1890

A Vindication of Natural Diet (original 1813) (link to archive.org) - new edition from 1884, with a preface by Henry S. Salt and W.E.A. Axon.

The life of Percy Bysshe Shelley: Vol.1 (link to google books)

The life of Percy Bysshe Shelley Vol.2 (link to google books) by Jefferson Hogg, pub. 1858 (in 4 volumes but only 2 finished). This is a much critcised biography, more about Hogg than Shelley.

Letters from Shelley to William Godwin Vol.1 - 1812 & 1816 (link to archive.org) - privately printed 1891

Letters from Shelley to William Godwin Vol.1 - 1816 to 1820 (link to archive.org) - privately printed 1891

Frankenstein, or, The modern Prometheus (complete) (link to Google Books, 1823 edition, 2 volumes in one scan) by Mary W. Shelley. Written 1816-17, first pub.1818. Revised 1831.

Letters from Shelley to Jane Clairmont (1816-1822) (link to archive.org) - privately printed 1889

The Shelley Society's papers. 1886-1888 (link to archive.org) - 20 articles by various authors

A Shelley Primer (link to archive.org) - by Henry S. Salt 1887

Shelley's Vegetarianism (link to archive.org) - by W.E.A.Axon, 1890

Shelley's principles; has time refuted or confirmed them? (link to archive.org ) by Henry S. Salt, 1892

Percy Bysshe Shelley, poet and pioneer; a biographical study (link to archive.org) - by Henry S. Salt, 1896

Peacock's memoir of Shelley, with Shelley's letters to Peacock (link to archive.org) - Thomas Love Peacock 1785-1866 - edited by H.F.B. Brett-Smith, 1909

The Complete Poetical Works of Percy Bysshe Shelley (link to archive.org) - ed by George Woodberry, 1901

Selected prose works of Shelley (link to archive.org) - edited by Henry S. Salt, 1915 - The necessity of atheism -- A letter to Lord Ellenborough -- A refutation of deism -- A defence of poetry -- Essay on the literature, the arts, and the manners of the Athenians -- On life -- On a future state -- Essay on Christianity

The Surgical Works Vol.2 (link to archive.org) by John Abernethy, pub, London 1811. 'Of Tumours' p.93: '...the power of the regimen recommend by Dr. Lambe should be fairly tried.'

Water and Vegetable Diet in Consumption, Scrofula, Cancer, Asthma, and Other Chronic Diseases (1815) by Dr. William Lambe, First Pub. London 1815 as 'Additional reports on the effects of a peculiar regimen in the cases of cancer, scrofula, consumption, asthma and other chronic diseases.' This edition 1850 New York with intro by Joel Shew M.D.p.90/91: "My reason for objecting to every species of matter to be used as food, except the direct produce of the earth, is founded as may be seen in my last publication on the broad ground that no other matter is suited to the organs of man, as indicated by his structure. This applies then with the same force to eggs, milk, cheese, and fish, as to flesh meat."

Bronson Alcott at Alcott House, England, and Fruitlands, New England (1842-1844) (link to archive.org) by F. B. Sanborn, 1908. Bronson Alcott (1788-1888)

The New Age - Concordium Gazette (link to Google Books) - from Alcott House, Ham Common, Surrey. Complete issues - May 1843 to December 1844

The board of health & longevity: or, Hydropathy for the people (link to google books) by William Horsell, London, 1845 - includes several uses of the word 'vegetarian'

Hydropathy for the People (link to archive.org) by William Horsell, written in England in 1845, with notes by Russell Trall M.D. for this New York, 1850 edition. Horsell hosted the founding meeting of The Vegetarian Society at his Hydropathic Hospital, Ramsgate, in 1847, and became the first Secretary.

The Truth Tester (1846-48) and The Vegetarian Advocate (1848-50) (html pages) published by William Horsell, Ramsgate then London. Became the official journal of The Vegetarian Society from Sept.1847. No full scan available, just extracts.

Punch magazine, 1848, Vol.XIV (link to google books) - this appears to be a combined volume for 1848. A sarcastic piece about The Vegetarian Society which was founded in September 1847.