Llandovery College has produced many thousands of well-rounded individuals who go on to excel in all walks of life. The school has also been the breeding ground for more than 40 international rugby players. Just some of our illustrious alumni are listed here:

• Alfred George Edwards (1848–1937), Archbishop of Wales
• Deian Hopkin (1944–), historian
• Carwyn James (1929-1983), Teacher and Coach at Llandovery College; rugby player and coach, Welsh international
• Vivian Jenkins (1911-2004), Welsh rugby and cricket international; sports journalist
• Mervyn Johns (1899-1992), film and TV actor
• Dill Jones (1923–1984), jazz pianist
• Ernest Jones (1879–1958), Welsh neurologist, psychoanalyst and official biographer of Sigmund Freud
• Gwyn Jones, Former Welsh International rugby captain
• Alun Wyn Jones (1985–), Welsh and British Lions international rugby player
• Rhodri Jones (1991 - ), Welsh International rugby player
• Charles Lewis, the second Wales international rugby union captain 1882-83
• James Merriman (1984–), Welsh U21, captain of Welsh 7s, squad member for World 7s victory in Dubai 2009
• George North (1992 -) Welsh International Rugby Player
• Rachel Poolman (1987–), Welsh international with 22 caps
• Andy Powell (1981–), Welsh and British Lions international rugby player
• Craig Quinnell (1975–), Welsh International rugby player
• William Rees (1808-1873), printer and publisher
• Llywarch Reynolds (1843–1916), Welsh solicitor and Celtic scholar
• Rod Richards (1947–), Conservative Party politician
• Rhydian Roberts (1983–), X-Factor runner up; former head boy; 1st XV
• Peter Rogers  (1969–), Welsh International rugby player
• David Vaughan Thomas (1873-1934), Composer
• Rhian Wyn Thomas (1988–), Welsh international golfer
• W. Llewelyn Williams (1867–1922), Liberal Party politician
• The Most Reverend G.O. Williams (1913–1990), Bishop of Bangor and Archbishop of Wales