Although Thahds are normally unintelligent, several Thahds over the course of the Geneforge series display enough intelligence and independence to have a noteworthy role in the player's adventures.
Rawbone was an enormous Thahd who led the rogue creations infesting the Ruined School on Sucia Island. Having discovered and donned a Student's Belt, his intellect was enhanced to the point that he could speak and make plans. He was able to use his intelligence and strength to gain a dominant position amongst the rogues in the School, which he referred to as his 'pets', and which appeared to worship him as some form of higher being. Rawbone was killed either by the Shipwrecked Apprentice or during the Shaper purge of Sucia Island.
Eliza's Mutated Thahd
A large Thahd designed by Eliza on the suggestion of Shaftoe. The Thahd had strong rogue tendencies, and was beyond Eliza's control. It constantly emitted poison, and was apparently comfortable in the toxic surroundings of the neglected chemical store of Eliza's Bunker. Its eventual fate is unknown, but it was likely killed either by the Double Agent, by Eliza herself, or by the successful Rebellion forces following the creation of the Unbound.