Purple Shadow Cobra

There is one tameable creature with this look.

Purple Shadow Cobra
Can Be Tamed
<Loa of Treachery>
Dusky Grotto, Ardenweald
Retains its original name after taming.
Appears during the Night Fae-only quest Cleansing the Forest, which is offered at renown level 8. These cobras appear later during the Dambala fight and you may need to use Aspect of the Turtle to avoid dying while taming. If you're in a shapeshifted form you'll also need to exit the form first. The quest appears to be phased to Night Fae only, so the Shadow of Dambala can only be tamed by a hunter in that covenant. If you miss out, it may be possible to tame one summoned during another Night Fae player's quest.
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.