Ryoth

Ryoth was a member of the High Council of the Time Lords. He was a member of the Arcalian Chapter and the Celestial Intervention Agency. When the Eighth Doctor was visiting his past selves, he attempted to kill the Eighth Doctor during his visit to his fifth incarnation by using the Time Scoop, but the Doctors were able to deactivate the Raston Warrior Robot he sent after them before turning it on the Sontaran battle group Ryoth sent when that failed. When he tried to unleash a Drashig on them, the Doctors were able to set up a Temporal Reverse Feedback Field that sent the Drashig to Ryoth instead. He was killed instantaneously and the Time Scoop destroyed. (PROSE: The Eight Doctors)