Giant Devourer.
actually made a suggestion to this effect a while back
https://forum-en.gw2archive.eu/forum/game/suggestions/Oversized-Pet-Grandmaster-Trait/first#post2704594
It’d be bumping an old thread, but if it interests you, show some support.
The fact of the matter is that we know devourers like this are tamable – the one in the image is tamed by charr, and there’s an event chain where you help an ogre chieftain tame one. So why can’t we get anything bigger than a terrier?