Alleyn is a surname, and may refer to:
- Charles Joseph Alleyn (1817-1890), Quebec lawyer and political figure
- Edward Alleyn (1566-1626), English actor
- James Alleyn (1683-1746), English educationalist
- John Alleyn (died 1686), surgeon and fifth Master of the College of God's Gift in Dulwich
- John Alleyn (1621-1663), British barrister and MP for Mitchell (Michael)
- Matthias Alleyn (died 1642), second Master of the College of God's Gift in Dulwich
- Raph Alleyn (died circa 1677), fourth Master of the College of God's Gift in Dulwich
- Roderick Alleyn, a fictional police detective
- Thomas Alleyn (3rd Master of Dulwich College) (died circa 1668), third Master of the College of God's Gift in Dulwich
- Thomas Alleyn (Barber-Surgeon) (died 1631), first Master of the College of God's Gift in Dulwich
John Alleyne may refer to:
- Sir John Alleyne, 1st Baronet (1724–1801), Speaker of the House of Assembly of Barbados
- Sir John Alleyne, 3rd Baronet (1820–1912), British businessman and engineer