The Black Guardian Trivia Quiz

Answer: Turlough

Vislor Turlough, an exile from his home planet Trion, worked with the Black Guardian in return for passage back to his home planet. Turlough tried several times to kill the Doctor, but each failed until Turlough decided he didn't want any more of this and temporarily vanquished the Black Guardian.

These events take up the span of three stories: "Mawdryn Undead", "Terminus", and "Enlightenment" and this trilogy is usually referred to as the "Black Guardian Trilogy".

Answer: The Key to Time

During the sixteenth season, all serials were loosely connected to one another. Each serial dealt with getting a different segment of the Key to Time before the Black Guardian could get to them and assemble them. With the Key to Time assembled and in the hands of the Black Guardian, the balance of the universe would become unstable.

Answer: Romana

Romana (when she was in her first incarnation) met the Black Guardian in "The Armageddon Factor". The Black Guardian tried to convince her and the Doctor to hand over the Key to Time, but the Doctor refused. The Black Guardian left but not before promising the Doctor that he will die for this.

It was Romana's only time meeting the Black Guardian, since she would leave before the Black Guardian would encounter the Doctor again.

Answer: His lack of concern over Princess Astra

Near the end of "The Armageddon Factor", the White Guardian appeared on the screen, congratulated the Doctor, and asked for the Key to Time. Princess Astra was one of the six segments to the key; however, the White Guardian wasn't concerned about this fact.

This tipped the Doctor off that the White Guardian wasn't who he said he was. It was the Black Guardian who was disguising himself as the White Guardian, so he would be able to own the Key to Time.

Answer: Attached a randomizer to the TARDIS

After defeating the Black Guardian, the Doctor wished to avoid him, so he decided to attach a randomizer to the controls of the TARDIS, which (as the name implies) meant the TARDIS would take the Doctor and his companion(s) to a random place. The randomizer was kept onboard the TARDIS until the story "The Leisure Hive" where it was needed to create a solution to the problem.

Despite this, it would be a couple more seasons until the Black Guardian caught up with the Doctor.

Answer: Brigadier Lethbridge-Stewart

Brigadier Lethbridge-Stewart retired from UNIT seven years prior to when (most of) the story takes place and decided to teach math at the same school that Turlough had been attending. He assisted the Doctor in reuniting with the TARDIS and his companions.
Originally, it was suppose to be Ian Chesterton, one of the Doctor's original companions, that was suppose to appear, but William Russell was unavailable. This would have made a little more sense, because it had previously been established that Ian was a teacher (he taught science).

Answer: Nyssa

On the space station, people were dying of a disease known as Lazar's disease. There was supposedly a cure but no one ever found it. Nyssa was exposed to Lazar's disease; however, she was able to get cured. Nyssa decided to stay behind on the space station to help the people there get cured and help them be able to run Terminus.

It was difficult for Tegan and the Doctor to accept, but they eventually allowed her to stay behind.

Answer: No

Turlough merely defeated, not killed, the Black Guardian after freeing himself from their deal. The White Guardian said that while one guardian exists, the other exists as well, and they will only cease to exist when they are no longer needed. He also said the Black Guardian would return angrier than ever, although he never did return, at least in the classic series.

Answer: fourth and fifth

The fourth Doctor first met the Black Guardian in "The Armageddon Factor", the last story in the "Key to Time" series. He was trying to get the Key to Time but the Doctor stopped him.
The fifth Doctor would meet the Black Guardian in "Enlightenment", the last story in the "Black Guardian Trilogy". He was trying to kill the Doctor, but when Turlough refused the crystal said to contain enlightenment, the Black Guardian disappeared.

Answer: Yes

While hanging onto to the Pharos Tower, he had flashbacks of several of his enemies that he encountered during his incarnation. The Black Guardian was among them; others include Daleks, Cybermen, Zygons, and Sontarans. The Doctor eventually fell off, which caused him to regenerate.

After falling off but prior to regenerating, he had flashbacks of previous companions calling out his name.