1. The Master
Could anyone else be at number one? A mainstay of the series since his first appearance in 1971, the Master is one of the Doctors greatest foes, if not the greatest. While the Doctor and the Daleks have an eternal hatred for one another, theres something else there with the Master; perhaps its fear. The Doctor is scared that one day he might just become the Master. More than just a Moriarty to the Doctors Sherlock Holmes, as he is so often described, the Master has evolved and changed over the years just as the Doctor has. In his first incarnation battling the Third Doctor, he was dry and urbane in his villainy. Next, an enemy of the Fourth to Seventh Doctors, he was more gleeful (some might say pantomimic, although endearingly so) at his increasingly complex schemes. In between, he became a proper monster, a dried out husk wanting nothing more than revenge something he returned to when facing the Eighth Doctor. John Simms regeneration set against the Tenth Doctor underwent the most development the character has had. A genius yet immoral and totally insane, it is revealed that through The Master's whole life he has been driven mad by a constant drum beat in his head (dont think too much about why he has never mentioned this to the Doctor before now). In The End of Time, he even got redemption by saving the Doctor, the Earth and the entirety of creation by helping send the Time Lords back to the Time War. Whatever his characterisation, though, be it suave villain or raving loon, the Master is definitely the most interesting Time Lord other than the Doctor. A massive fan of the Meddling Monk? Feel I've been a bit harsh by not including the War Chief? Why not materialise your thoughts on my choices in a comment below.