Lamont

Sister Lamont was Harry Sullivan's nurse when he was shot on the head by The Caber.

As a Zygon
Nurse Lamont was for the most part of her interactions with Harry and the others a Zygon in disguise who whilst in the hospital, attacked Sarah Jane Smith and placed her a decompression chamber.

The Zygon posing as Sister Lamont also went to the inn and killed Huckle and then retrieved to the surveillance device from the deer's head.

Whilst in the Zygon's spacecraft the Doctor found the real Lamont and along with the other humans who had been taken by the Zygons and copied, he helped them escape prior to destroying the Zygon's craft. (DW: Terror of the Zygons)