Special Executive

The Special Executive were a mercenary group of bizarre superpowered lifeforms, led by Wardog, who worked across time and the multiverse.

One account has it that they were the first creations by Rassilon's Looms, imbued by time energies, only to be disowned by him. (Walking in Eternity)

They were hired by Gallifrey, in the early days of the Time Lords, to retrieve the assassin Fenris. Wardog, alongside Time Lady Rema-Du, did the retrieval, and Viridian the Brainfeeler scanned Fenris' mind to identify his employers as the Order of the Black Sun. At that moment, agents of the Order attacked; Viridian was killed and Wardog had his left arm blown off. (DWM: 4-D War)

Ten years later, the Executive - Wardog, Zeitgeist, Cobweb and Millenium - escorted Rema-Du to a trade negotiation that involved the Sontarans and a third party. The third party turned out to be the Order from before they declared war on Gallifrey. The Sontarans brainwashed Millenium with a psy-snare and had her murder the Black Sun representative. Wardog killed her in a failed attempt to stop the murder - and because the Executive were employed by the Time Lords, the Order of the Black Sun believed this to be a deliberate assault and declared war. (DWM: Black Sun Rising)

The unofficial Walking in Eternity contained a story where they abandoned Gallifrey when the Loom-created Newborn rose up against the "Womb born", feeling no kinship with the former and knowing they couldn't effectively help the latter.

Behind the scenes
Alan Moore, their creator, did not write any further Doctor Who strips, preventing him from using most of the material he had planned for the Executive. He went on to use them in the Captain Britain strip of Marvel UK's The Daredevils - one of multiple crossovers between Marvel Comics and Doctor Who by the UK branch. They made two cameos in Marvel's Excalibur, the first showing that Wardog was the second leader of the Executive.