Vexillum is a genus of small to medium-sized sea snails, marine gastropod molluscs in the family Costellariidae.

[2] It is considered a "dumping ground" for an array of unrelated forms.

[3] The shell is elongated, turreted, longitudinally ribbed or plicate.

[4] Vexillum species produce complex venoms dominated by highly diversified short cysteine-rich peptides, vexitoxins, related to conotoxins.

[5] This genus is cosmopolitan and occurs in tropical and temperate seas, but primarily in shallow waters (but also at bathyal depths) of the tropical Indo-Pacific.