Walsh (The Zygon Invasion)

Colonel Walsh was a UNIT colonel and the leader of a strike team on a Zygon-infested building in Turmezistan.

When the Twelfth Doctor arrived in Turmezistan, Walsh ordered a missile strike on a Zygon-infested town, but their drone operator Lisa called off the strike on her own due to her seeing her husband and son in the town and unable to continue the strike. Instead, Walsh opted to lead a strike team on the building in Turmezistan where the Zygons were hiding.

The Doctor accompanied Walsh and the soldiers to the town. Walsh and the Doctor hid behind a building while her soldiers ordered the Zygons to surrender. However, the Zygons tricked the soldiers into thinking that they were their loved ones, and Walsh's troops were killed.

Inside the building, Walsh went looking for the Zygons while the Doctor followed Osgood's voice. (TV: The Zygon Invasion)