James Robert ("Jamie") McCrimmon

One of the Second Doctor's companions, Laird Colin McLaren's piper.   The Second Doctor met him soon after the Battle of Culloden in 1746.  He then helped the Time Lord, Ben and Polly escape from Gray's sinister clutches.  He stayed with the Second Doctor throughout the rest of his incarnation, traveling first with Ben and Polly, then with Victoria, and finally with Zoe.  Jamie helped the Doctor fight Professor Zaroff, the Cybermen, the Macra. the Chameleons, the Dalekx, the Great Intelligence, and the Yeti, the Ice Warriors, Salamander and the Weed.  Just after that, when the Doctor had left Victoria with the Harrises, the Time Lord (or, more likely, the Celestial Intervention Agency) pulled the Doctor and Jamie out of their normal timelines and sent them off to Space Station J7 to deliver a warning to Dastari about unauthorized time experiments.  Jamie helped the Sixth Doctor and Peri fight Chessene and the Sontarans, and became the target of Shockeye's antrophagous lust.  Afterwards his memories of the mission were erased by the Time Lords.  During his travels with Zoe, Jamie helped the Doctor fight the Cybermen, the Dominators, the Master Brain of the Land of Fiction (who altered Jamie's physical appearance), the krotons, and Caven's space pirates.  After taking part in the War Games, Jamie was returned by the Time Lords to his own era, just after the end of his first adventure with the Doctor.  Jamie's image was used by Rassilon to ward off the Second Doctor.