Here is a notable selection:
- Romanadvoratrelundar, aka Romana, traveled with the Fourth Doctor in her first and second incarnations, and later became president of the Time Lords
- The Master, another renegade Time Lord and a long-time enemy of the Doctor.
- Susan Foreman, the Doctor's granddaughter, who travelled with him in his first incarnation (never said on screen, but it can be inferred)
- Rassilon, one of the founders of time lord society
There's also the Monk, the Rani, the War Chief, the Corsair, Borusa, Omega, Morbius, K'anpo Rimpoche, Andred, Spandrell, Goth, and Flavia.