Llewellin is a Welsh surname derived from the personal name Llwelyn. Notable people with the surname include:
Ben Llewellin (born 1994), Welsh sports shooter David Llewellin (born 1960), Welsh rally driver John Llewellin, 1st Baron Llewellin GBE, PC, MC, TD (1893–1957), British army officer, Conservative Party politician Llewelyn Llewellin (died 1878), the first Dean of St David's Cathedral Philip Llewellin (1940–2005), British journalist and writer Richard Llewellin (born 1938), retired Anglican bishop in the Church of England
See also Llewellin Setter, strain of English setters bred by R.L. Purcell Llewellin to be perfect for foot hunting and early field trials Llewelen Llywelyn