Grogg

From Teletraan I: The Transformers Wiki

Grogg is an alien in the Blackthorne portion of the Generation 1 continuity family.

Grogg has guarded the library planet of Andellor and the Power Prism for a millennium. An invader only has to survive chambers full of worm creatures and answer a riddle:

"It cannot be touched, tasted, seen, or heard; it might not exist at all, except that its strength has laid low the greatest titans. All live under its reign, and eventually fleshling, Autobot, and Decepticon will all fall before its just hand. What is this?"

Well, at least the worm creatures are tough.