Zygon McGillop

A Zygon was part of the group stuck on Earth. Their ship landed in 1562, but the group retreated into a stasis cube and stayed there until the 21st century, where this Zygon took McGillop's form.

Later, three of the Doctors[[ erased the memories of both the humans and their Zygon counterparts, and peace was restored. ([[TV: The Day of the Doctor)