Felix Vaughan (7 Mar 1766 – 22 April 1799) was an English barrister, known as defence counsel in the treason trials of the 1790s.
The son of Samuel Vaughan of Middlesex, a tradesman, he was baptized at St James Westminster 20 Mar 1766, educated at Harrow School and Stanmore, where briefly he was a pupil of Samuel Parr, who became a lifelong friend, as did Basil William Douglas, Lord Daer, a schoolfellow, son of Dunbar Douglas, 4th Earl of Selkirk. He was admitted to the Inner Temple in 1785. He entered Jesus College, Cambridge as a fellow-commoner in 1786, graduating B.A. in 1790 and M.A. in 1794.
Vaughan was in France and Geneva in 1790–1. He corresponded from the continent with John Richter and William Frend.
Back in England, Vaughan was part of the London radical milieu including James Losh, also one of the group dining with John Horne Tooke. He was called to the bar in 1792. In spring of that year he was involved in drafting the constitution of the London Corresponding Society (LCS). and consulted about with the Society for Constitutional Information. He became a dedicated LCS member, much involved in legal matters.
From early in 1793, judicial measures, some questionable procedurally and some seen to be over severe, were used to repress reforming views. In July Vaughan successfully defended a Knutsford bookseller who had stocked works of Tom Paine. Advising James Watt junior, then abroad, Vaughan took the view that he was safe from prosecution. He was counsel, with John Gurney, for Thomas Briellat, convicted in December 1793 for using seditious language. In making the defence case, Vaughan emphasised the ubiquity of the Association for Preserving Liberty and Property.