lemming

noun2

1. •
   A small arctic and subarctic rodent of the tribes Lemmini, Dicrostonychini and Lagurini.
2. •
   (figurative) Any member of a group given to conformity or groupthink, especially a group poised to follow a leader off a cliff.

   • Lemmings are strongly cohesive, but could be, in organisational terms, highly destructive for the business. — 2004