Nixie may refer to:
- Nixie tube, a gas-filled electron tube once in use as an alphanumeric display
- Neck (water spirit) or Nixie, a mythical water creature in Germanic folk tales
- Melusine or Nixie, a mythical feminine spirit of fresh waters in sacred springs and rivers
- Nixie (Dungeons & Dragons), a creature from Dungeons & Dragons
- AN/SLQ-25 Nixie, a torpedo decoy
- Nixie (postal), a piece of undeliverable mail, or the postal marking on such a piece of mail