Eldest and possibly only daughter of Lord Rust.
With the disgrace and exile of her brother Gravid to Fourecks, after he had been found to have been using goblins as slaves and smuggling lethal troll drugs into Ankh-Morpork, Regina is set to inherit her fathers position and title upon his death.
Given that Lord Rust is now ill and infirm it seems likely she will soon become Lady Rust and have control of the Rust family and power. Lord Vetinari complained to Commander Vimes about this, stating that he would have preferred to have dealt with her brother Gravid, who is lazy idiot rather than his forceful and astute sister. Once rather feels he protests too much, and might relish the challenge. But it is unlikely Regina will make life easy for Sam Vimes or Vetinari, as it is to be expected she will hold them responsible for her brother’s exile and slight to her family and try to exact revenge.