Bemar

Bemar was the tyranic ruler of the Human colony planet Publius and served the Druden.

Ruler of Publius
Whilst on the way to Publius during the time of the Second Galactic Empire, Bemar became the next ruler by mysteriously deposing the planned leaders one by one. (DWA: Plague World)

Plague
Bemar served the insectoid race the Druden when they invaded the planet. When the Druden infected the planet with the plague, Bemar was given an antidote to survive the disease so to be able calm the people down as they were disappearing and fed to the Druden younglings.

When the Doctor, Adric and K9 arrived on the planet and entered the assembly which was held, Bemar accused them for being the cause of all the trouble after Adric spoke out. The Doctor who quickly deactivated K9 so he couldn't be used was able to escape thanks to Kidson who opposed Bemar and Adric was chained up. (DWA: Plague World)

Death
When the Doctor and Kidson stopped the Druden with Kidson sacrificing himself to destroy them, before Bemar could teleport the Druden to the village the Doctor activated K9 through a signal which once activated K9 used his photon beams on her destroying the transmitter and presumably killing her. (DWA: Plague World)