Dillwyn may refer to the following:
Places Dillwyn, Kansas, an unincorporated community in Stafford County Dillwyn, Virginia, an incorporated town in Buckingham County
People with the surname Amy Dillwyn (1845-1935), Welsh novelist Lewis Llewelyn Dillwyn (1814-1892), Welsh industrialist and Liberal politician Lewis Weston Dillwyn (1778-1855), British porcelain manufacturer, naturalist and MP Mary Dillwyn (1816–1906), early Welsh photographer Mary De la Beche Nicholl (née Dillwyn) (1839–1922), lepidopterist and mountaineer William Dillwyn (1743–1824) American-born British Quaker and abolitionist
People with the given name Dillwyn Parrish (1894—1941), American writer, illustrator and painter Dilly Knox, born Alfred Dillwyn Knox (1884–1943), British codebreaker John Dillwyn Llewelyn (1810–1882) Welsh botanist and photographer Thereza Dillwyn Llewelyn (1834–1926) astronomer and photographer William Dillwyn Sims (1825–1895) English industrialist and artist