Hemal

Hemal was a Time Lord who served as Lord Cardinal on the High Council of Gallifrey. However, he was secretly a member of a cult that worshipped Rassilon as a vampire. After the cult found an ancient strand of Vampire DNA, Hemal stole it and turned himself into a Vampire. At one point, he murdered a Time Lord, as part of a lure to the Doctor. He sent a distress call to the Doctor under the pretense of investigating a murder. It was soon found the murder had been committed by a vampire.

Hemal infiltrated the Doctor's TARDIS, and infected Tegan with a bite. While the Doctor was able to calm her down, Hemal took control of his TARDIS, and announced he planned to spread vampirism throughout time and space, with his first destination being London on Earth. However, Nyssa discreetly altered the coodinates, so that the TARDIS landed at 10.00 AM, in perfect sunlight. Hemal was killed, and his infection of Tegan was reversed. (COMIC: Blood Invocation)

Behind the scenes
Discounting Kevin Lindsay's yellowface portrayal of Cho-Je in 1974, with his 1994 debut Cardinal Hemal was the first Time Lord depicted as a person of colour.