Veche's servitor. Definitely a person.
Rather than go through the hassle of reprogramming a new servitor when the old one is destroyed, Veche has Zippy regularly backed up onto a cogitator so that its subroutines can simply be uploaded to a new, identical servitor (also named Zippy). It is unknown how many iterations of Zippy there have been, however it periodically displays some odd quirks, such as most recently when it collaborated with the Steed of Gallophus to try and sacrifice itself in order to destroy a chaos-tainted Leman Russ and save its master’s life.
Unbeknownst to Enginseer Veche Xanatov, the first Zippy was a servitor of Magos Biologis Vechelin Aloysius Xanatov (who followed the same backup procedure), and its occasional hidden depths are likely a result of its long service to the Xanatov geneline.