Greyhound

Greyhound was a commonly used call sign in UNIT.

Simply Greyhound was used at various points by Alistair Gordon Lethbridge-Stewart, (TV: The Mind of Evil, The Claws of Axos, The Dæmons, The Time Monster, The Green Death, Battlefield) John Benton, (TV: Terror of the Autons) and Mike Yates. (TV: Day of the Daleks)

Greyhound Leader was used by Brigadier Lethbridge-Stewart. (TV: Robot, Terror of the Zygons) It was also once used by Benton when he answered on behalf of the Brig. (TV: Robot)

Greyhound One was also used by the Brigadier. (TV: The Green Death, Invasion of the Dinosaurs, Battlefield)

Greyhound Two was used by both the Brigadier (TV: The Dæmons) and Captain Yates. (TV: Day of the Daleks)

Yates used Greyhound Three whilst transporting the TARDIS to the Newton Institute. (TV: The Time Monster) Benton also used this sign. (TV: The Green Death)

Jo Grant once used Greyhound Four. (TV: The Green Death)

Doctor Martha Jones used Greyhound Six. (TV: The Sontaran Stratagem)

A UNIT soldier once used the call sign Greyhound Seven. (TV: The Mind of Evil)

In Donna's World, the call sign of Private Harris was Greyhound Fifteen. (TV: Turn Left)

Greyhound Sixteen was used by Steve Gray. (TV: The Sontaran Stratagem)

Greyhound Forty was used by Ross Jenkins (TV: The Poison Sky) and on one occasion by the Tenth Doctor using Jenkins' radio. (TV: The Sontaran Stratagem)