| Honorific Prefix: | The Right Honourable |
| The Viscount Clifden | |
| Office: | Member of Parliament for County Kilkenny |
| Term Start: | 1857 |
| Term End: | 1874 |
| Predecessor: | John Greene William Shee |
| Successor: | George Leopold Bryan Patrick Martin |
| Birth Name: | Leopold George Frederick Agar-Ellis |
| Birth Date: | 13 May 1829 |
| Birth Place: | London, England |
| Alma Mater: | Trinity College, Cambridge |
| Parents: | George Agar-Ellis, 1st Baron Dover Lady Georgiana Howard |
| Relations: | Henry Ellis, 2nd Viscount Clifden (grandfather) George Howard, 6th Earl of Carlisle (grandfather) |
Leopold George Frederick Agar-Ellis, 5th Viscount Clifden (13 May 1829 – 10 September 1899), known as Leopold Agar-Ellis until 1895, was a British Liberal politician.
Born in London, Clifden was the second son of George Agar-Ellis, 1st Baron Dover, and the eldest son of Henry Ellis, 2nd Viscount Clifden. His mother was Lady Georgiana, daughter of George Howard, 6th Earl of Carlisle. He was educated at Trinity College, Cambridge, and was called to the Bar, Inner Temple, in 1854.
Between 1855 and 1858 and 1859 and 1864 Clifden served as Aide-de-Camp to the Lord-Lieutenant of Ireland, his uncle the Earl of Carlisle. He also served as Member of Parliament for County Kilkenny from 1857 to 1874. In 1895 he succeeded his nephew as fifth Viscount Clifden and fourth Baron Dover and entered the House of Lords.
On 8 February 1864, Agar-Ellis was married to the Hon. Harriet, daughter of Thomas Stonor, 3rd Baron Camoys and Frances Towneley (only daughter of Peregrine Edward Towneley). Together, they were the parents of:
He died in London in September 1899, aged 70. He had no surviving male issue and the barony of Dover became extinct on his death. The viscountcy of Clifden and barony of Mendip were passed on to his second cousin, Thomas Agar-Robartes, 2nd Baron Robartes. Lady Clifden died in May 1914, aged 78.[1]