Spem in alium is a 40-part Renaissance motet by Thomas Tallis, composed in c. 1570 for eight choirs of five voices each. It is considered by some critics to be the greatest piece of English early music. H. B. Collins described it in 1929 as Tallis's "crowning achievement", along with his Lamentations.

Thomas Tallis was an English composer of High Renaissance music. His compositions are primarily vocal, and he occupies a primary place in anthologies of English choral music. Tallis is considered one of England's greatest composers, and is honoured for his original voice in English musicianship.