Madra

Madra was a Zygon who used the body-print of Harry Sullivan to collect the trilanic activator from the temporary UNIT base. Madra's odd behaviour alerted Sarah Jane Smith to the fact that he was not the real Harry, and she and two UNIT soldiers pursued him. Madra fled to a barn, where in the hay loft he menaced Sarah with a pitchfork. However, a particularly forceful thrust towards Sarah, and her stepping aside to avoid this, saw Madra fall from the loft and become impaled on his own weapon; he changed back into a Zygon as he died. In order to avoid discovery, Broton had the body molecularly dispersed. (TV: Terror of the Zygons)