Colonel was a military rank.

On Earth, it was above lieutenant-colonel and below brigadier. (TV: The Web of Fear, The Invasion)

Colonels in the British Army included Ackroyd, (HOMEVID: Unnatural Selection) Archer, (TV: Resurrection of the Daleks) Attwood, (TV: The Highlanders) Hugh Curbishley, (TV: The Unicorn and the Wasp) Alistair Gordon Lethbridge-Stewart, (TV: The Web of Fear) T.P. Potter, (PROSE: Illegal Alien) George Radlett, (PROSE: The English Way of Death) Edmund Ross, (PROSE: Evolution) James Skinsale, (TV: Horror of Fang Rock) George Trenchard, (TV: The Sea Devils) Warburton (PROSE: All-Consuming Fire) and Wilson. (PROSE: The Burning)

Colonels in UNIT included Ross Brimmicombe-Wood, (AUDIO: The Wasting) Emily Chaudhry, (AUDIO: Time Heals) Charles Crichton, (TV: The Five Doctors) Faraday, (TV: The Android Invasion) Muriel Frost, (COMIC: Evening's Empire) Tia Karim, (TV: Death of the Doctor) Katayev, (PROSE: The Devil Goblins from Neptune) Alan Mace, (TV: The Sontaran Stratagem/The Poison Sky) Augustus Oduya, (TV: Children of Earth) Philips, (PROSE: The Pit) Vikram Shindi, (AUDIO: Armageddon) Walsh (TV: The Zygon Invasion) and Wilson. (HOMEVID: Auton 2: Sentinel)

Colonels in the Wehrmacht included Kessler (COMIC: Me and My Shadow) and Schott. (PROSE: Illegal Alien)

Colonels in the US Army included Jack Finney (PROSE: First Frontier) and Stark. (TV: Dreamland)

Colonels in the Church included Albero, Meme (TV: The Time of the Doctor) and Manton. (TV: A Good Man Goes to War)

Morgan Blue was a colonel in the Combined Galactic Resistance. (TV: Into the Dalek)

Marc Forest was a colonel in the Space Security Service. (PROSE: The Outlaw Planet)

Kortez was a colonel in UNISYC. (PROSE: Alien Bodies)

L. V. Mortimer was a colonel in the United States Marine Corps. (PROSE: White Darkness)

Murash was a colonel in the Thal military. (AUDIO: Guilt)

Nasgard was a colonel in the Kaled Military Elite. (AUDIO: Innocence)

Samran was a colonel in Iraq. (PROSE: Eternity Weeps)

Sarg (PROSE: The Taking of Chelsea 426) and Snathe (COMIC: The Betrothal of Sontar) were Sontaran colonels.

Adam Shade was a colonel in the Anti-Terror Elite. (PROSE: Ten Little Aliens)

Sty was a colonel in the Bolkon Context. (PROSE: The Doctor Trap)

White was a colonel in the Dione-Kisumu Company. (PROSE: Sleepy)

Ben Wolsey was a colonel in Sir George Hutchinson's war games. (TV: The Awakening)