Blacktail Wrasse
Thalassoma ballieui
- Least concern
- Card rarity: Common
- Fish

The blacktail wrasse, also known as Ballieu's wrasse, is a species of wrasse native to the waters around the Hawaiian Islands and Johnston Island. It is a reef dweller found at depths from 1 to 60 m. It can reach 39.5 cm (15.6 in) in length. It can also be found in the aquarium trade.
Classification
- Class
- Actinopterygii
- Order
- Labriformes
- Family
- Labridae
- Genus
- Thalassoma