Description
Okay fine, I lied. I have one more. To be fair though, she's a cyborg and not entirely a robot.
Lore time!
The Borg-Federation Accord of 2541 allowed a compromise that effectively ended all Borg hostilities. It allows the Borg to continue assimilation only on a voluntary basis, and that drones taken against their will to decide whether to remain in the collective.
As most sentients do not look upon the idea of giving up their individuality fondly, the Borg have become more reliant on reproducing within their own ranks. Genetic material is gathered from drones and zygotes are conceived in-vitro, before being implanted into specialized Gestation Units, essentially autonomous versions of the previously used Borg Maturation Chambers.
Fourth of Four (or as she’s known as to non-Collective associates “Fourty-four”) is one such GU, as well as being an engineer and organic technician (medic).
(please forgive if this contradicts canon at all, I'm not 100% caught up with the mythos)