Ghostly White Hydra

There is one tameable creature with this look.

Ghostly White Hydra
Can Be Tamed
Bittertide Lake, Sholazar Basin
Retains its original name after taming.
Spawns during the Oracles daily quest A Cleansing Song. This quest is given by Oracle Soo-nee and isn't up every day. You can only take this quest if you're at least Friendly with The Oracles.
* Level scaling: In Shadowlands most NPCs will scale with the Hunter's level, within the constraints of their level range. Hunters can tame regular NPCs up to 2 levels higher than them, but can only tame elite NPCs of the hunter's level or below.