Locutus of Borg

Borg leader created by the assimilation of Jean-Luc Picard into the Borg consciousness in 2366. Although the concept of a Borg leader was, at the time, almost a contradiction in terms, Locutus was intended to provide a voice for the Borg, as part of a Borg plan to assimilate the Federation. With Picard's mind in the Borg collective consciousness, the powerful adversary had access to all of Picard's knowledge and experience, making him partially responsible for the massive Federation defeat at the battle of Wolf 359. But the access proved to be two-way. The capture of Locutus by the Enterprise-D personnel gave them access to the Borg collective consciousness, and they were able to defeat the Borg by exploiting this access.

Locutus was to have been a voluntary counterpart of the Borg queen, with a mind of his own, not just another Borg drone. She wanted Picard to give himself freely to the Borg, but he resisted and was forced into the collective.