The Master

A time Lord,he can regenerate, which means his body changes,he is the Doctors greatest enemy,he is different,he his cruel and cold-hearted,the Doctor is a female time Lord, which is basically a time Lady,The Master enjoys seeing people in pain and doubt,he plans to to destroy Earth,which The Doctor is not going to let happen and she will do anything to protect Earth, putting her life at cost, Time Ladies and Time Lords can regenerate and they kind-hearted unlike The Master,The Master enjoys killing people and is extremely smart like the other Time Lords and Time Ladies,Time Lords and Time Ladies have 2 hearts,he can outsmart people,at first The Doctor fell for his tricks because he was using someones identity, hiding away from The Doctor, leaving her unsuspicious,he was the Doctor's old best friend,but it washed away a long time ago..