John Sidney Linnell (born June 12, 1959) is an American musician, known primarily as one half of the Brooklyn-based alternative rock band They Might Be Giants. In addition to singing and songwriting, he plays accordion, baritone and bass saxophone, clarinet, and keyboards for the group.

Linnell’s lyrics include strange subject matter and word play. Persistent themes include aging, delusional behavior, bad relationships, death, and the personification of inanimate objects. Conversely, the accompanying melodies are usually cascading and upbeat.