Abnormal brain

The abnormal brain is one of the brains that can be found in the Sierra Army Depot and be used to build a mobile body structure for Skynet. However, using the abnormal brain makes Skynet so stupid that it can only act as a pack horse. Although you can issue commands to it, it will not leave your party unless you kill it.

Appearances
The abnormal brain only appears in Fallout 2.

Behind the scenes
The abnormal brain and its acquisition are a reference to the movie Young Frankenstein where Igor accidentally destroys the optimal brain for the titular scientist's monster and takes a brain labelled "Abnormal" (which he reads as "Abby Normal") instead.