Allyn is both a unisex given name and a surname. Notable people with the name include:
- Given name
- Leigh-Allyn Baker (born 1972), American actress, director and voice artist
- Allyn L. Brown (1883–1973), American judge
- Allyn Capron (1846–1898), US Army captain
- Allyn K. Capron (1871–1898), first US Army officer to die in the Spanish–American War
- Allyn Condon (born 1974), English sprinter
- Allyn Cox (1896–1982), American painter
- Allyn Sue Danzeisen, American–New Zealand community leader
- Allyn Ferguson (1924–2010), American composer
- Allyn Joslyn (1901–1981), American stage, film and television actor
- Ruth Allyn Marcus (born 1958), American journalist and political commentator
- Allyn McKeen (1905–1978), American college football coach
- Allyn Ann McLerie (1926–2018), American dancer
- Francis Allyn Olmsted (1819–1844), American author
- Wayne Allyn Root (born 1961), American businessperson
- Allyn Rose (born 1988), American beauty pageant titleholder and model
- J. Allyn Rosser (born 1957), American poet
- Allyn Stout (1904–1974), American Major League baseball pitcher
- Allyn Vine (1914–1994), American physicist and oceanographer
- Allyn Abbott Young (1876–1929), American economist
- Surname