There was a season five Star Trek: Enterprise
episode pitched where a human Starfleet medical technician played by Alice Krige makes contact with the 22nd century Borg, is assimilated and becomes the Borg Queen. It was supposed to explain her obsession with Earth and humans.
I can imagine some fans being furious at the idea of that, but I think it would have been cool. Maybe Archer blew her body to smitheens or something.
Personally I think the Queen is a manifestation of the Borg's directives and goals. I think she was made her a bit too petty and human, though (which the ENT episode would have justified)