The War Lord
With the help of Time Lord technology stolen by a Time Lord renegade known as the War Chief, the War Lord set up the War Games. A vast operation which involved kidnapping thousands of Earth soldiers from various wars for purpose of training an unbeatable army with which the War Lord planed conquer the galaxy. The War Games were discovered by the Doctor who was able to put a stop to them, but, unable to return so many people to their proper places in time and space, the Doctor was forced to contact the Time Lords. Captured by the Time Lords, the War Lord was tried and summarily dematerialized. The War Lord's planet was forever sealed in a time loop by the Time Lords.
The War Chief
Name given by the War Lord to the renegade Time Lord who brought him the secret of time travel (inferior TARDISes known as SIDRATS) in exchange for power. During the War Games, he recognized the Doctor and asked him to join forces. After the Doctor called the Time Lords, he tried to escape, but was shot and presumably killed by one of the War Lord's men