  We summarize the potential of high--energy $\ee$ linear colliders for
discovering, and in case of discovery, for studying the signals of extended
gauge models. We will mainly focus on the virtual signals of new neutral gauge
bosons and on the production of new heavy leptons. [Invited talk given at the
Workshop on Physics and Experiments with Linear Colliders, Morioka-Appi, Japan,
September 8-12 1995.]
