According to Yoshihisa Tsuda (who worked as a designer for X2) a proposed idea for Zero's origin is that he was originally Roll who got kidnapped and modified by Wily
Thank goodness whoever came up with that proposal failed. Canonically they are robots, but the metaphor they would create is quite clear and would demonstrate ignorance about the very topic they would clearly be pushing.
Shadowplay and Impurata are a sonuvabitch. And then RIGHT at the end of Dark Cybertron, the old Senator personality emerged for a brief second of clarity before he died.