Null-A Three, usually written Ā Three, is a 1985 science fiction novel by A. E. van Vogt. It incorporates concepts from the General semantics of Alfred Korzybski and refers to non-Aristotelian logic. The novel is a continuation of the adventures of Gilbert Gosseyn from The World of Null-A (1945) and The Pawns of Null-A (1948).