Colonel is an Old English Sheepdog who lives on a farm in the English countryside with his two companions: Captain, a horse, and Sergeant Tibbs, a tabby cat. The trio seem to function as a pseudo-military unit, with Colonel as the commanding officer. Colonel has a tendency to mispronounce words. However, he has a fighting spirit and is courageous.
Colonel is first referenced by Old Towser, a bloodhound living at Whithermarsh. After Towser receives the news that the Dalmatian puppies are missing, Towser relays the message to the Colonel, as Colonel is the only dog in range. Lucy the goose notes to Towser that the message must be loud and clear, or Colonel would never get it.
After being alerted to the message, Colonel initially mishears spotted puppies as "spotted puddles," though a double check confirms the message. Captain and Tibbs note activity at the nearby Hell Hall (the Old De Vil Place) that has been abandoned for years. Colonel and Tibbs go to investigate. While Colonel waits outside, Tibbs goes into the house to learn that the 15 stolen puppies are there, along side 84 that have been bought by Jasper and Horace Badun as well as Cruella De Vil. Although Tibbs is discovered by Jasper, he escapes and relays the message to Colonel, who sends it back down the Twilight Barking Chain.
Later, after learning that Pongo and Perdita are on their way to find the puppies, the Colonel and Tibbs continue to be on the alert for more news until one day, they see a car making its way to Hell Hall, prompting them to go back there to investigate. Tibbs goes back in the manor and learns of Cruella De Vil's plan to skin the puppies, so he plans to help the puppies escape from Hell Hall, but their escape is noticed by the Baduns, who give chase. The Colonel, meanwhile, meets up with Pongo and Perdita, and informs them of the situation. He then watches the two parents fight the Baduns from outside, and later helps Tibbs lead the puppies back to the farm.
At the farm, Colonel and the others learn that Jasper and Horace are following their tracks. Colonel suggests fighting them, but Pongo and Perdita decide to take the puppies and run. They thank Colonel, Captain and Tibbs, who note that it was all in the line of duty. When Jasper and Horace arrive, Colonel leads them to believe that the puppies are hiding in the hay. This puts the two Baduns in position to be kicked by Captain, which postpones their tracking of the Dalmatians.
Although Colonel doesn't appear in the film afterwards, it can be presumed that he passed the news of the Dalmatians' journeying home through the Twilight Barking Chain and calling all dogs to be on the lookout, which would explain why the Collie was able to find them and offer them shelter at his dairy farm.
Colonel made a cameo as McDuff, the sheepdog of a laundry man named Roger Baskerville in the episode, "Pound of Baskervilles" where the Rescue Rangers helped him to find the will of Lord Howard Baskerville.
The Colonel makes a cameo in the live-action adaptation of the film when Cruella sets off to find the puppies, after Jasper and Horace had lost them. In the movie, the Colonel is instead called "Fogey." While asleep in the barn, Fogey is awakened by Punch (the Captain), who was the first to receive the Twilight Bark message about the stolen puppies. As he rallies the farm animals together, an Airedale terrier arrives, informing them on seeing a number of Dalmatian pups being abducted. The farm animals deduce that those must be the same ones the Twilight Bark is referring to. As Kipper heads out to help the puppies, Fogey then barks an urgent message, which is received by the canines of London.
Fogey is later seen helping Kipper with the Dalmatian pups by leading them from De Vil Manor and sneaking them into the barn, having some sheep cover the puppies when Cruella drives around looking for them. Fogey then shows Pongo and Perdita where the Dalmatians pups are; they are seen with the cows, drinking milk from their udders. It is possible that Fogey is there when Cruella confronts the farm animals in the barn while she is looking for the puppies.
Colonel is an elderly sheep dog who has seen and done many things during his lifetime. When Cruella De Vil attempted to steal Pongo and Perdita's Dalmatians in an attempt to slaughter them and use their fur in her fashion designs, he was one of the individuals responsible for helping resolve the issue and return the Dalmatians home without incident; though Colonel's loyal friend, Sergeant Tibbs, also assisted in that endeavor. Colonel now spends his time resting on the Dearly Farm, as he is quite old and he no longer has the same physical endurance that he had when he was younger, though he directly oversees many operations in the Bark Brigade and Sergeant Tibbs keeps him well informed of the issues that he doesn't know of. In his spare time, Colonel enjoys telling stories of things that occurred in his past to the Dalmatians who stop by to visit them, despite the fact that the Dalmatians aren’t always interested in hearing what he has to say, though he also instills morals into the Dalmatians to help them see the error of their ways, or to realize that they need to do something better in the future. Despite the fact that he is slowly becoming less and less important around the Dearly Farm, due to his age, he remains one of the most respected figures and he has done everything he can to ensure the Bark Brigade succeeds in its mission.