Arts

• Carmen Llywelyn, American actress and photographer
• Chris Llewellyn (poet), American poet
• David Llewellyn (author) (born 1978), Welsh author of Eleven
• Desmond Llewelyn (1914–1999), Welsh actor who played Q in several James Bond films
• Dylan Llewellyn, English actor
• Grace Llewellyn, American author of several books on homeschooling
• Kate Llewellyn (born 1936), Australian poet
• Morgan Llywelyn (born 1937), U.S.-born Irish historical author
• Olivia Llewellyn (born 1980), English actress
• Patricia Llewellyn (1962–2017), British television producer
• Richard Llewellyn (1906–1983), English author of Welsh descent
• Robert Llewellyn (born 1956), English actor, presenter, and writer
• Roddy Llewellyn (born 1947), British landscape gardener, author, and television presenter
• Roger Llewellyn, British actor
• Sam Llewellyn (born 1948), British author of literature for children and adults
• Sheila Llewellyn (born 1948 or 1949), novelist from Northern Ireland
• William Llewellyn (painter) (1858–1941), English painter and President of the Royal Academy

Politics

• Evan Henry Llewellyn (1847–1914), British politician
• Karl Llewellyn (1893–1962), American jurisprudential scholar
• Margaret Llewelyn Davies (1861–1944), British social activist
• Royce R. Lewellen, California Superior Court judge
• Theodora Llewelyn Davies (1898–1988), British barrister and penal reform campaigner

Sports

• Bert Llewellyn (1939–2016), English footballer
• Carl Llewellyn (born 1965), Welsh jockey and trainer
• Charlie Llewellyn (1876–1964), first non-white South African Test cricketer
• Chris Llewellyn (born 1979), Welsh footballer
• Gareth Llewellyn (born 1969), Welsh rugby union footballer
• Harry Llewellyn (1911–1999), British equestrian champion
• Steve Llewellyn (1924–2002), Welsh rugby league footballer
• Willie Llewellyn (1878–1973), Welsh international rugby captain

Other

• David Llewellyn (disambiguation), several people
• Doug Llewelyn (born 1938), original host of The People's Court
• John Dillwyn Llewelyn (1810–1882), Welsh botanist and photographer
• Morgan Llewellyn (1937–2024), British Army officer
• Paula Llewellyn, Jamaican lawyer
• Peter Rodney Llewellyn (born 1947), English businessman and con artist
• Reese J. Llewellyn (c. 1862–1936), Welsh-born American businessman

Middle Ages

Ordered chronologically

• Llywelyn ap Merfyn (died 942), king of Powys
• Llywelyn Aurdorchog (c. 1005–1065), Welsh war-chief, lord of Ial
• Llywelyn ap Seisyll (died 1023), king of Gwynedd and Deheubarth
• Llywelyn the Great (Llywelyn Fawr; Llywelyn ab Iorwerth; c. 1173–1240), Prince of Gwynedd and ruler of most of Wales
• Llywelyn Fawr ap Maredudd, early 13th century lord of Meirionnydd
• Llywelyn ap Gruffudd (c. 1228–1282), last crowned Welsh Prince of Wales
• Llywelyn ap Maredudd ap Llywelyn ap Maredudd ap Cynan (died 1263), minor Welsh prince, last vassal lord of Meirionnydd
• Llywelyn ap Dafydd (c. 1260–1288), heir to the Welsh crown imprisoned in 1283
• Llywelyn Bren (died 1317), nobleman who led a Welsh rebellion in 1316
• Llywelyn ap Gruffydd Fychan (1341–1401), Welsh landowner executed for assisting Owain Glyndŵr's escape from English forces

Arts

• Llywelyn Goch ap Meurig Hen (c. 1350–1390), Welsh-language court poet
• Llywelyn ab y Moel (died 1440), Welsh-language poet and rebel
• Llewelyn Wyn Griffith (1890–1977), Welsh novelist
• Llewelyn Powys (1884–1939), British writer
• Llywelyn Siôn (c. 1540–1615), Welsh-language poet
• Llewellyn Xavier (born 1945), Saint Lucian artist

Military

• Llewellyn Chilson (1920–1981), highly decorated United States Army master sergeant
• Llewellyn Garrish Estes (1843–1905), American Civil War soldier awarded the Medal of Honor
• Llewellyn F. Haskell (1842–1929), Union Army officer
• Llewelyn Alberic Emilius Price-Davies (1878–1965), British soldier and recipient of the Victoria Cross

Politics

• Llewellyn Atherley-Jones (1851–1929), British politician and judge
• Llewellyn L. Callaway (1868–1951), chief justice of the Montana Supreme Court
• Llewellyn Edwards (born 1935), Australian politician and chancellor of the University of Queensland
• Llewellyn Powers (1836–1908), member of the US House of Representatives from Maine
• Llewellyn H. Rockwell, Jr. (born 1944), American libertarian political commentator
• Llewellyn Thomas Smith (Llew Smith) (born 1944), Welsh politician
• Llewellyn Thompson (1904–1972), American diplomat
• Llewellyn Turner (1823–1903), Welsh politician
• Llywelyn Williams (1911–1965), Welsh politician

Sports

• Llewelyn Alan Curbishley (born 1957), English football manager
• Llewellyn Herbert (born 1977), South African athlete
• Llewelyn Kenrick (1847–1933), Welsh international footballer
• Llewellyn Starks (born 1967), American long jumper

Other

• Llewellyn John Montfort Bebb (1862–1915), British academic
• Llewellyn Henry Gwynne (1863–1957), first Bishop of Egypt and Sudan
• Llewelyn Lewellin (1798–1878), British cleric and university educator
• Llewellyn Ivor Price (1905–1980), Brazilian paleontologist
• Llewellyn Thomas, British physicist and applied mathematician
• Llewellyn Vaughan-Lee (born 1953), British Sufi mystic and author
• Llewelyn Williams (disambiguation)
• Llewellyn Woodward (1890–1971), British historian