Lammasu

When asked if all the returning Legendary creatures were 'evil' in Zoom 2020-10-29 21:00, DM replies, 'No, Lammasu have also been reported'.
As Matt pointed out, "Lammasu seem a really unlikely candidate for the ire of the elves – “It is the nature of these creatures to aid and protect lawful good persons and they are of generally kind and friendly disposition to all good creatures.”  They can also communicate via (limited) telepathy and are of genius level intelligence."
So they could be a very useful source of information if we able to meet one.