Thahd Shades are Thahds that are part organic and part Shade. They are the only shade creation that players have been able to create themselves in the Geneforge series.
In Geneforge 1 and 2, Thahd Shades are the "upgraded" Thahds, becoming available as a creation once one gets a skill of 3 in Create Thahd. Starting in Geneforge 3, the Thahd Shade is replaced with the Unstable Thahd.
Aside from having a higher base level than Thahds, Thahd Shades are harder to hit than Thahds. As well, they are immune to most mental effects and do not take damage from poison.